UCDP/PRIO Armed Conflict Dataset
Codebook1
Version 4-2007
Uppsala Conflict Data Program (UCDP)
www.ucdp.uu.se
International Peace Research Institute, Oslo (PRIO)
www.prio.no

When using the data, please cite Gleditsch et al. (2002) and (when appropriate) this codebook.
Please always include the version number in analyses using the dataset. When referring to thedataset, make sure to use the correct name: the UCDP/PRIO Armed Conflict Dataset.

1

The first release of the Armed Conflict Dataset was prepared at PRIO in 2002 in close collaboration
with researchers at the Department of Peace and Conflict Research at Uppsala University and theDepartments of Sociology and Political Science and Geomatics at the Norwegian University of Scienceand Technology (NTNU). For a description of the division of labor in creating the database, see the firstfootnote in Gleditsch et al. (2002: 615). This footnote also lists the financial sources of support for theentire project and credits for comments and advice received along the way.
This is version 4-2007 of the codebook and associated documents. We are grateful to several
colleagues and external users for constructive comments. For our policy on version labeling, see Section
2.3 below, and for a complete history of earlier versions see the document called Version History. For
further comments and suggestions on the data and the codebook, please communicate both to project
leader in Uppsala Lotta Harbom (lotta.harbom@pcr.uu.se) and to jpr@prio.no.

This version compiled and updated by:
Lotta Harbom
Uppsala Conflict Data Program (UCDP)
In collaboration with
Halvard Buhaug
Joachim Carlsen &Håvard Strand
International Peace Research Institute, Oslo (PRIO)
Earlier versions and definitions:Peter Wallensteen
Birger Heldt
Margareta Sollenberg
Mikael Eriksson &Stina Högbladh
Uppsala Conflict Data Program (UCDP)
Nils Petter GleditschHåvard Hegre &Lars Wilhelmsen
International Peace Research Institute, Oslo (PRIO)

12

Introduction ....................................................................................................................4
Definition of conflict ......................................................................................................4
2.1
Armed Conflict .......................................................................................................4
2.2
Missing data problems ............................................................................................5
2.3
Version name convention........................................................................................63
The main conflict table ...................................................................................................6
3.1
ID ...........................................................................................................................8
3.2
Location..................................................................................................................8
3.3
SideA......................................................................................................................8
3.4
SideA2nd ................................................................................................................9
3.5
SideB ......................................................................................................................9
3.6
SideB2nd ................................................................................................................9
3.7
Incomp....................................................................................................................9
3.8
Terr.......................................................................................................................10
3.9Year ......................................................................................................................10
3.10 Int .........................................................................................................................10
3.11 CumInt..................................................................................................................10
3.12 Type......................................................................................................................10
3.13 Startdate................................................................................................................11
3.14 Startprec................................................................................................................11
3.15 Startdate2..............................................................................................................11
3.16 Startprec2..............................................................................................................11
3.17 EpStart ..................................................................................................................11
3.18 EpEnd ...................................................................................................................11
3.19 EpEndDate............................................................................................................12
3.20 EpEndPrec ............................................................................................................12
3.21 GWNoA................................................................................................................13
3.22 GWNoA2nd..........................................................................................................13
3.23 GWNoB................................................................................................................13
3.24 GWNoB2nd ..........................................................................................................13
3.25 GWNoloc..............................................................................................................13
3.26 Region ..................................................................................................................13
3.27 Version .................................................................................................................13
4
System Membership description ...................................................................................14
5
References ....................................................................................................................19

1 Introduction
This document describes the UCDP/PRIO Armed Conflict Dataset, a joint project between the
Uppsala Conflict Data Program (UCDP) at the Department of Peace and Conflict Research,
Uppsala University and the Centre for the Study of Civil War at the International Peace ResearchInstitute in Oslo (PRIO). The dataset was first presented in Gleditsch, Wallensteen, Eriksson,
Sollenberg&
Strand(2002),
andisavailablefordownload
fromwww.prio.no/cscw/armedconflict and www.pcr.uu.se/research/UCDP/our_data1.htm.
The project is part of the larger Uppsala Conflict Data Program, which is thoroughly described atwww.ucdp.uu.se.
Both UCDP and PRIO offer a range of other datasets, compatible with the UCDP/PRIO
dataset. For more information on available data, visit the web pages referenced above.
Version x is updated in accordance to the changes listed in Harbom & Wallensteen (2006), andthe 2006 conflicts have been added to the database. We refer the reader to our Version History
document for details of other changes and revisions to the dataset. The dataset will continue tobe updated with new data annually.

2 Definition of conflict
The main unit in this dataset is an “Armed Conflict” as defined by UCDP.2 This definition ispresented unabridged in section 2.1. Each conflict is listed in the database and given a unique ID
code. The temporal aspect of a conflict is not addressed by this definition; hence, two conflict
episodes over the same incompatibility will be assigned the same ID regardless of the time
separating them. See below for further clarifications.

2.1 Armed Conflict
UCDP defines conflict as: “a contested incompatibility that concerns government and/or
territory where the use of armed force between two parties, of which at least one is thegovernment of a state, results in at least 25 battle-related deaths.”
The separate elements of the definition are operationalized as follows:(1) Use of armed force: use of arms in order to promote the parties’ general position in theconflict, resulting in deaths.
(1.1) Arms: any material means, e.g. manufactured weapons but also sticks, stones, fire,
water etc.
(2) 25 deaths: A minimum of 25 battle-related deaths per year and per dyad (see 3.3) in an
incompatibility.3(3.1) Party: A government of a state or any opposition organization or alliance oforganizations. UCDP distinguishes between primary and secondary parties.
Primary parties are those that form an incompatibility by stating incompatible
positions (see 5). At least one of the primary parties is the government of a state.
2

For a more in-depth discussion on definitions, see http://www.pcr.uu.se/database/definitions_all.htm#i
Note that an incompatibility involving two opposition groups, each involved in clashes with the government
resulting in 20 deaths, would not be recorded as a conflict (neither dyad reached the minimum casualty
threshold), whereas an incompatibility involving a single opposition group that caused 25 battle-deaths would be
included in the dataset. Due to lack of precise information, the coding of some conflicts prior to 1989 include
opposition organisations that may not fulfil the 25 battle-related deaths criterion.
3(3.2)
(3.3)

(3.4)

Secondary parties are states that enter a conflict with troops to actively support
one of the primary parties. The secondary party must share the position of the
primary party it is supporting in the incompatibility.
Government: The party controlling the capital of a state.
Opposition organization: Any non-governmental group of people having announced
a name for their group and using armed force to influence the outcome of thestated incompatibility (see section 5). The UCDP only deals with formallyorganized opposition. The focus is on armed conflict involving consciously
conducted and planned political campaigns rather than spontaneous violence.
Dyad: A dyad consists of two conflicting primary parties. At least one of the
primary parties must be the government of a state. In interstate conflicts, bothprimary parties are state governments.4 In intrastate and extrasystemic conflicts,
the non-governmental primary party includes one or more opposition
organization(s). A conflict can include more than one dyad. If e.g. a governmentis opposed by three rebel groups over the same incompatibility, the conflict ismade up of three dyads. Note that secondary parties (i.e. intervening states
supplying troops to one of the primary parties) do not lead to the formation of
additional dyads.

(4) State: A state is an internationally recognised sovereign government controlling a
specific territory or an internationally unrecognised government controlling a specified
territory whose sovereignty is not disputed by another internationally recognizedsovereign government previously controlling the same territory. See section 4 for details
on the sample of countries covered by this definition.
(5) Incompatibility concerning government or territory: The incompatibility, as stated by the parties,
must concern government and/or territory.
(5.1)
Incompatibility: The stated general incompatible positions.
(5.2)
Incompatibility concerning government: Incompatibility concerning type of politicalsystem, the replacement of the central government, or the change of its
composition.
(5.3)
Incompatibility concerning territory: Incompatibility concerning the status of aterritory, e.g. the change of the state in control of a certain territory (interstate
conflict), secession or autonomy (internal conflict).
For information on how these elements and definitions are connected to the different fields inthe dataset more precisely, see Section 3.

2.2 Missing data problems
The missing data code is -99. However, the dataset does not include unclear conflicts where
information on key variables to the definition of conflict is uncertain or missing. Key variables
are those related to the incompatibility, actors and intensity. In addition, a number of events havebeen identified as potentially in accordance with the criteria for inclusion. These events include
possible new dyads and additional years for active conflicts. Consult the list of unclear cases forfurther information.
The information also varies with regard to the level of precision. For the start date variables,
the precision level is indicated in a separate variable, see 3.14 and 3.16. Apart from that, the4With three exceptions, the primary parties in interstate conflicts consist of only one actor on each side (and thus
only constitute one dyad). See description of Location below for further information on these cases.

dataset only includes information when we are quite confident that it is correct. The bias
produced by this approach is against the inclusion of conflicts in the earlier decades and in theless-developed world. An armed conflict in a developed country in the 1990s is more likely to berecorded than a conflict in a less developed country in the 1950s.

2.3 Version name convention
This codebook corresponds to version x of the UCDP/PRIO database. For every new release,substantial changes will be documented in a separate document. 5 This should be helpful toresearchers trying to replicate a particular study. We recommend that whenever this dataset isused, the version number should be cited.
The version number is a combination of a number and a year. The number is increased when
the structure of the dataset is significantly changed The year refers to when the dataset is updatedwith new observations. If there are changes in the data between yearly updates, a letter is usedbehind the year.

3 The main conflict table
The observation (or unit) in the Main Conflict table is the conflict-year. Each conflict is listed inall years where fighting in one or more dyad(s) caused at least 25 battle-related deaths. This is incontrast to Version 2.1 (and earlier versions) of the dataset.6
The calendar year is the basic unit of every observation. Thus, if a conflict during the period
June–September results in 30 casualties, that year will be recorded as a year of conflict. However,if the same number of casualties occurred in the period November–February and the conflict
failed to reach the threshold of 25 battle-related deaths in either calendar year, neither year will be
coded as in conflict. This has a number of consequences that will be discussed below. Start dates
frequently refer to years prior to the first calendar year of a conflict, as the start of a conflictmight be in a year with less than 25 casualties. Small conflicts might not be included. Certain
observations might be based on a single event, such as the Omagh bombing in Northern Ireland
in 1998, which exceeded the minimum threshold for armed conflict.
Table 1. Definition of variables in the Main Conflict Table
Variable
Label
Description
ID
Conflict identifier
The unique identifier of all conflicts
The name(s) of the country/countries
Location
Country name(s)whose government(s) have a primary
claim to the issue in dispute.
Identifying the country/countries ofside A in a conflict. Always the
SideA
Country name(s)government side in internal conflicts.
Note that this is a primary party to theconflict.
5

http://www.ucdp.uu.se/research/UCDP/our_data1.htm andhttp://www.prio.no/cscw/armedconflict/version_history.pdf
6
The previous formulation read ‘The observation (or unit) in the database is a conflict-year, a subconflict, or asubset of either over a period of time where no element in the definition described in Section 2 is changed. Eachconflict is likely to include several observations’. This definition of the primary unit made sense in the text lists
that preceded this dataset, where space was an important issue. The data structure was kept in order to staycompatible with previous versions. But while this might be advantageous to old users, it has confused a numberof new users. The new annual data structure therefore replaced the old structure in Version 3.0.

SideA2nd

SideB

SideB2nd
Incomp
Terr
Year

Int

CumIntType
Startdate
Startprec
Startdate2
Startprec2
EpStartDate
EpEnd
EpEndDate
EpEndPrec
GWNoA
GWNoA2ndGWNoB

Name of states supporting Identifying
the country/countries
side A with troops.
supporting side A in the conflict.
Identifying the opposition actors or
country/ countries of side B in theCountry
name(s)or conflict. In an internal conflict, thisOpposition actors
includesmilitary
opposition
organizations. Note that this is a
primary party to the conflict.
Name of state(s) supporting Identifying
the country/countries
side B with troops.
supporting side B in the conflict.
Conflict Incompatibility
A general coding of the conflict issue
The name of the territory over which
Name of territory
the conflict is fought, provided that theincompatibility is territory.
Year of observation
The intensity level of the conflict per
calendar year. Two different intensity
Intensity level
levels are coded: minor armed conflicts
and wars. See Section 3.10 for
definitions of the two categories.
The intensity of the conflict, taking into
Cumulative intensity
consideration the conflict history.
Four different types of conflict:extrasystemic, interstate, internal andConflict typeinternationalized internal. See Section
3.12 for definitions of the four types.
The date, as precise as possible, of theDate of conflict initiation
first battle-related death in the conflict.
The level of precision for the initial
Precision of startdate
date.
The date, as precise as possible, when
the conflict for the first time reached
Date of fatality threshold
25-battle-related deaths in a calendar
year.
Precision of startdate2
The level of precision for startdate2.
The date, as precise as possible, when
Date of initiation of conflict the latest episode of conflict activity
episodereached 25 battle-related deaths in a
year.
Codes whether this is the last year of
Episode ended
conflict activity in this episode
Date when conflict activity The date, as precise as possible, whenendedconflict activity ended.
Episode end precision
The level of precision for episode end.
GW numbers of all countries on side
GW number(s) of side AA, separated by semicolons.
GW number(s) of states GW numbers of all countries
supporting side A.
supporting side A with troops.
GW numbers of all countries on side B,
GW numbers of side B
separated by semicolons.

GWNoB2nd
GWNoloc
RegionVersion

GW numbers of
supporting side B.

states GW numbers of all countries
supporting side B with troops.
GW numbers of all location countries,
GW number of location
separated by semicolons.
Identifying the region of the location.
Region of location
See Section 3.22 for the definition of
the regions.
The current version of the dataset. See
Version number
Section 2.3.

3.1 ID
Conflict identifier. To download a conversion table containing new and old IDs, visit
www.prio.no/cscw/armedconflict.

3.2 Location
Location is defined as the government side of a conflict, and should not be interpreted as thegeographical location of the conflict.
• For internal and internationalized internal conflicts (see 3.12 for definition), only one country
name is listed. This is the country whose government or territory is disputed. For certain
conflicts, such as Kurdistan, the disputed territory is divided between different countries.
Following our definition, we have coded separate conflicts for each country.
• For interstate conflict, both primary parties are listed in the Location field. Even if several
governments are involved in the conflict, only countries that fulfill the inclusion criteria forprimary actors are listed here. This normally means that two countries are listed, but there arethree notable exceptions: In the Arab-Israeli war of 1948–49 as well as the Suez war of 1956
and the war in Iraq in 2003, there are more than two primary parties to the conflict.
• For extrasystemic conflicts, Location is set to be the disputed area, not the government of thecolonial power. Since the Location field in these conflicts by default does not indicate
members of the international system, it constitutes an exception from the definition presented
in Section 2.
Location is a string variable, listing the names of the countries involved. These might be fighting
together or against each other. The string is split in two ways, hyphen (‘-‘) splits the different
sides in an interstate war, and comma (‘,’) splits different countries fighting together on the sameside.

3.3 SideASide A is by definition always a primary party to the conflict. In internal conflicts, side A is always
the government side, it is one of the sides in interstate conflicts and the colonial state in
extrasystemic conflicts.
Side A is a string variable, and in the few cases where there are more than one primary party onside A (see section 3.3), these are separated by a comma (‘,’).

3.4 SideA2nd
Side A Secondary lists all states that enter a conflict with troops to actively support side A in theconflict. By definition, only independent states can be a secondary party in conflict. A secondary
party on side A shares the position in the incompatibility with Side A in the conflict. Side A
Secondary does not need to meet the 25 battle-related deaths criterion to be included in thedataset; an active troop participation is enough.
Side A Secondary is a string variable, where the different names are separated by a comma (‘,’).

3.5 SideB
Like Side A, Side B is by definition a primary party to the conflict. Side B is the opposition sideof all internal and extrasystemic conflicts and the second side in an interstate conflict. Thus, Side
B can include both states and non-governmental opposition groups, depending on the type of
conflict. When the primary party listed on Side B is an opposition group, the column lists thegroup name in abbreviated form. We refer to the conflict list for the full name of oppositiongroups.
Side B is a string variable, where the different names are separated by a comma (‘,’).

3.6 SideB2nd
Side B Secondary lists all states that enter a conflict with troops to actively support side B in theconflict. Only states are included as Side B Secondary. Furthermore, the states listed share theposition in the incompatibility with Side B in the conflict. Side B Secondary does not need tomeet the 25 battle-related deaths criterion to be included in the dataset; an active troop
participation is enough. Note that when there is more than one opposition organization listed in
an internal conflict, the dataset does not provide information on which of these groups the state
coded as Side B Secondary is supporting.
Side B Secondary is a string variable, where the different names are separated by a comma (‘,’).

3.7 Incomp
As a country can experience several simultaneous conflicts, it is essential to differentiate between
them. As described in Section 2.1, UCDP collects information on conflicts where theincompatibility, i.e. the general incompatible positions, concerns either government, territory or
both. Earlier versions of the UCDP/PRIO dataset only contained two incompatibility categories,
territory and government. Conflicts that concerned both territory and government were assigned
to their primary incompatibility. From version X, the incompatibility is coded in three categories:
1 Territory
2 Government
3 Government and Territory
Note that the incompatibility expressed in terms of government or a specific territory is crude in
the sense that possible underlying incompatibilities are not considered. In other words, the statedincompatibility is what the parties are (or claim to be) fighting over, but it says nothing about why
the parties are fighting.
While a state can only experience one intrastate conflict over government in a given year, thatsame state can simultaneously be a primary party to one or more interstate conflicts over
government and/or territory. In the case of intrastate territorial conflicts, multiple conflicts canbe recorded over different territories in a state in a given year.

3.8 Terr
If the incompatibility is territory, the disputed territory will be listed here. In case the two sides
use different names for the disputed territory, the name listed is the one used by the opposition
organisation. One reason for this is that this is most often the name that the general publicrecognises. Another reason is that there are cases where the disputed territories do not have anofficial name. This is the case in e.g. conflict ID 227, a territorial conflict in north-eastern India.
The rebel organisation NDFB is fighting for independence for a territory that is a part of
the Assam region, and does not have an official, separate name. Thus, we use the rebel's name forthe territory: Bodoland.

3.9 Year
The year of observation.

3.10 Int
The intensity variable is coded in two categories:7
1. Minor: between 25 and 999 battle-related deaths in a given year.
2. War: at least 1,000 battle-related deaths in a given year.

3.11 CumInt
This variable takes into account the temporal dimension of the conflict. It is a dummy variable
that codes whether the conflict since the onset has exceeded 1,000 battle-related deaths. A
conflict is coded as 0 as long as it has not over time resulted in more than 1,000 battle-related
deaths. Once a conflict reaches this threshold, it is coded as 1.

3.12 TypeWe define four types of conflict:
1. Extrasystemic armed conflict occurs between a state and a non-state group outside its own
territory. (In the COW project, extrasystemic war is subdivided into colonial war andimperial war, but this distinction is not used here.) These conflicts are by definition
territorial, since the government side is fighting to retain control of a territory outside thestate system.
2 Interstate armed conflict occurs between two or more states.
3. Internal armed conflict occurs between the government of a state and one or more internal
opposition group(s) without intervention from other states.
4. Internationalized internal armed conflict occurs between the government of a state and one ormore internal opposition group(s) with intervention from other states (secondary parties)
on one or both sides.

7

In earlier versions of the UCDP/PRIO dataset, the intensity variable contained three categories: minor,
intermediate and war. The intermediate category was defined as “more than 25 battle-related deaths per year anda total conflict history of more than 1000 battle-related deaths, but fewer than 1000 per year.” Thus, the variable
included a temporal dimension into the intensity coding. However, as many users incorrectly interpreted thevariable as ordinal, it was decided that the intermediate category should be represented by a separate dummy
variable denoting cumulative intensity.

3.13 Startdate
The date of the first battle-related death recorded in the conflict is coded as the Startdate in thedataset. The date is set after the conflict fulfills all criteria required in the definition of an armed
conflict, except for the number of deaths. In some cases, the initial fatality occurs in a year prior
to the first year of activity. For instance, in the conflict in Uzbekistan (conflict ID 221), the first
battle-related deaths occurred in February 1999. During the remaining months of 1999, theconflict did not reach the required 25 battle-related deaths threshold and the conflict is thus
coded as inactive in 1999. 25 battle-related deaths were not recorded until the following year. A
conflict is assigned a new value on Startdate whenever there is a complete change on the
opposition side.8

3.14 Startprec
The Startdate is coded as precisely as possible. For certain conflicts we can pinpoint the start of
the armed conflict down to a single event, taking place on a specific day. For other conflicts, thisis not possible, due to lack of precise information.
The Startprec (start precision) is coded to highlight the level of certainty for the date set in theStartdate variable.
1. Day, month and year are precisely coded; we have good information on the event.
2. Day is assigned; month and year are precisely coded. The assigned date can either be one ofseveral events that can be classified as the first; it can be the last day in a period when several
fatalities have been reported jointly or it can be an event that different sources claim occurredon different dates.
3. Day is unknown; month and year are precisely coded. The day is known to be in a given
month, but we are missing information on an exact date. Day is then set to the first day of themonth.
4. Month is assigned; year is coded precisely. Day is set as the first day of the assigned month.
5. Day and month are unknown, year is coded precisely. Day and month are set as the 1
January of the coded year.
6. Year is assigned. There is a wide disagreement between different sources, so that not evenyear can be coded precisely. The start year is assigned based on subjective judgment.
7. Year is missing. No information on the start date is available; Startdate is set to 1 January of
the first year recorded in the conflict.

3.15 Startdate2
The first time the conflict reaches 25 battle-related deaths in one calendar year. Startdate2 thus
indicates the date that the conflict fulfills all criteria required in the definition of an armed conflictfor the first time. In case precise information is lacking, Startdate2 is by default set to 1
January (or identical to StartDate if the first fatality occurred later in the year).

3.16 Startprec2
In cases where Startdate and Startdate2 indicate the same year, the precision codes for Startdate2,
Startprec2, follows the same logic as for Startprec. However, if Startdate and Startdate2 represent
8
For various reasons, the coding of start dates and start precision are not conducted in an entirely consistentmanner. This will be corrected in future versions of the dataset.

different years, values 11–17 are assigned. This ensures that information on both the precision
for the date given for Startdate 2 and its relation with Startdate are provided. For instance, aStartprec2 of 11 indicates that the precision score is 1 and that the start date 1 was in aprevious year. A Startprec2 of 12 means that the precision score is 2 and that the start date 1
was in a previous year, etc. See 3.14. for explanations on the precision scores. Note: If theconflict was active (i.e. fulfilled all inclusion criteria) before 1946, Startdate2 is set to 1 January ofthat year and Startprec2 is given the precision score 17.

3.17 EpStartDate
This variable and the three that follow (3.18-3.20) refer to episodes (or periods) within
conflicts and are new to version 4-2007 of the dataset. Variables 3.17 – 3.19 are taken directlyfrom UCDP’s Conflict Termination Dataset.9 The introduction of episodes within conflicts
enables users to distinguish between different phases in the conflict and, potentially, codethese as separate conflicts. An episode is defined as continuous conflict activity involving a
constant or overlapping set of actors on Side B. Consequently, a new episode is coded
whenever a conflict restarts after one or more year(s) of inactivity or if there is a completechange of actors on the opposition side. EpStartDate provides the date of a new episode.
During the first period of a conflict, the EpStartDate is identical to Startdate2, i.e. it indicatesthe date when the conflict reaches 25 battle-related deaths in a calendar year for the first time.
For later episodes, the EpStartDate lists the date when the new conflict episode reaches thefatality threshold. In line with the Conflict Termination Dataset, EpStartDate is set to 1
January (or identical to StartDate if the first fatality occurred later in the year) if more precise
information is lacking.

3.18 EpEnd
EpEnd is a dummy variable that codes whether the conflict is inactive the following year and an
episode of the conflict thus ends. If the conflict is inactive the following year(s), this variable iscoded as 1. If not, a 0 is coded.

3.19 EpEndDate
This variable is only coded in years where EpEnd has the value 1. If a conflict year isfollowed by at least one year of conflict inactivity, the EpEndDate variable lists, as precise as
possible, the date that violence stopped. If detailed information is lacking the Conflict
Termination Dataset sets the date to 31 December.

3.20 EpEndPrec
For version 4-2007 of the dataset, this variable is missing and thus assigned the value -99.
Episode End Precision will be introduced in future versions of the dataset.

9
For a presentation of the dataset, see Kreutz, “How armed conflicts end” (unpublished manuscript). Bothmanuscript and dataset can be found at http://www.pcr.uu.se/research/UCDP/our_data1.htm. For coding rules
and more detailed definition of these variables please see the Conflict Termination Dataset’s code book.

3.20 GWNoA
To facilitate analytical use of the dataset, country codes for the active state(s) on side A are listed
in this field. The country codes are taken from Gleditsch & Ward (1999).
In line with 3.4, in internal conflicts GWNoA lists the country code of the government; ininterstate conflicts it arbitrarily lists one of the states and in extrasystemic conflicts it lists thecode for the colonial state. This variable may contain more than one country.
GWNo A is a string variable, where the numbers are separated by a comma (‘,’).

3.21 GWNoA2nd
GWNo A Secondary lists the country codes for the states coded in Side A Secondary (3.5).
GWNo A Secondary is a string variable, where the numbers are separated by a comma (‘,’).

3.22 GWNoB
GWNoB lists the country codes for states coded in Side B. GWNoB is only coded in interstate
conflicts, since that is the only time a state is active on side B. (see 3.4-3.7)
GWNoB is a string variable, where the numbers are separated by a comma (‘,’).

3.23 GWNoB2nd
GWNoB2nd lists the country codes for the states coded in Side B Secondary (3.7).
GWNo2nd is a string variable, where the numbers are separated by a comma (‘,’).

3.24 GWNoloc
This field contains the country code(s) for the state(s) listed in the Location variable. Thus, it lists
the country codes for the primary party/parties in the conflict.
GWNoloc is a string variable, where the numbers are separated by a comma (‘,’).

3.25 Region
Region of location.
ID
1
2
3
4
5

Name
EuropeMiddle East
Asia
AfricaAmericas3.26 Version
See 2.3

StartGWNo
200
630
700
400
2

EndGWNo
395
698
990
625
165

4 System Membership description
The definition of a state is crucial to our conflict list. State: A state is(a) an internationally recognized sovereign government controlling a specified territory, or(b) an internationally unrecognized government controlling a specified territory whosesovereignty is not disputed by another internationally recognized sovereign government
previously controlling the same territory.
The conflict definition is based upon participating governmental actors of independent states,
and the classification of a given conflict rests heavily upon the status of the different actors. In
order to define the total population of states we use the Gleditsch & Ward (1999) systems
membership definition, which is based on the Correlates of War project. Gleditsch & Ward
include countries with a population of more than 250,000 that have ‘a relatively autonomous
administration over some territory’, and is ‘considered a distinct entity by local actors or the state
it is dependent on’ (Gleditsch & Ward, 1999: 398).
The Gleditsch & Ward definition differs from our original definition in two main ways. First, for
Gleditsch & Ward a state is considered to be a new entity if it is ‘considered a distinct entity by
local actors’ while the conflict definition only recognizes it as a new entity when the ‘sovereignty
is not disputed by another internationally recognized sovereign government previously
controlling the same territory’. Second, the Gleditsch & Ward states all have a population of
more than 250,000 while our conflict definition does not prescribe a specific size of the
population.
In a few cases, countries with less than 250,000 inhabitants experience conflict or are active as
secondary parties in a conflict. In those cases we use the Gleditsch & Ward tentative list of
microstates. For example, the microstate Tonga was part of the multinational coalition fighting in
Iraq in 2004.
The UCDP/PRIO dataset includes one political entity that lacks a country code (GWNoA is set
at -99) as it is excluded from both the Gleditsch & Ward system membership table and thetentative list of microstates: Hyderabad (Hyderabad vs. CPI and Hyderabad vs. India). In 1947
when England granted India independence, a cabinet memorandum declared that the Princely
States were free to decide to either join India or Pakistan before August 1947 - or devise theirown sovereign political system for self-governance. Hyderabad declared itself independent on 15
August 1947. The state was populated by approximately 15,000,000 inhabitants. The systemmembership ended when Hyderabad was annexed by India in September 1948, after Winston
Churchill had proposed to the United Nations to consider it as an independent state.
In a few cases, the dataset have a different sovereignty date for some countries that haveexperienced conflict:
Croatia
Gleditsch & Ward 25 June 1991 declares independence
UCDP/PRIO
27 April 1992 the new constitution of Yugoslavia
Bosnia-Herzegovina Gleditsch & Ward
UCDP/PRIO

3 Mars 1992
declares independence
27 April 1992 the new constitution of Yugoslavia

Azerbaijan

30 August 1991 becomes independent
21 December 1991

Gleditsch & Ward
UCDP/PRIO

Gleditsch & Ward use a slightly modified version of the COW numbering system. The tablebelow presents the system membership table that we base our data tables on. These data are
updated through 31 December 2005 by us, based on the assumption that no country has enteredor left the international system after the most recent version of the Gleditsch & Ward data.
Table 2. List of system members since 1946
StateNum
2
20
31
53
40
41
42
51
52
70
80
90
91
92
93
94
95
100
101
110
115
130
135
140
145
150
155
160
165
200
205
210
211
212
220
225
230
235
260
265
290
305
310
315
316
317
325

StateAbb
USA
CAN
BHM
BAR
CUB
HAI
DOM
JAM
TRI
MEX
BLZ
GUA
HON
SAL
NIC
COS
PAN
COL
VEN
GUY
SUR
ECU
PER
BRA
BOL
PAR
CHL
ARG
URU
UK
IRE
NTH
BEL
LUX
FRN
SWZ
SPN
POR
GFR
GDR
POL
AUS
HUN
CZE
CZR
SLO
ITA

StateName
United States of America
CanadaBahamasBarbados
Cuba
Haiti
Dominican Republic
Jamaica
Trinidad and Tobago
MexicoBelizeGuatemalaHonduras
El Salvador
Nicaragua
Costa Rica
PanamaColombia
Venezuela
GuyanaSurinamEcuador
Peru
BrazilBoliviaParaguay
Chile
Argentina
Uruguay
United Kingdom
IrelandNetherlands
Belgium
Luxembourg
FranceSwitzerland
Spain
Portugal
German Federal Republic
German Democratic Republic
PolandAustria
Hungary
Czechoslovakia
Czech Republic
Slovakia
Italy/Sardinia

StartYear
1946
1946
1973
1966
1946
1946
1946
1962
1962
1946
1981
1946
1946
1946
1946
1946
1946
1946
1946
1966
1975
1946
1946
1946
1946
1946
1946
1946
1946
1946
1946
1946
1946
1946
1946
1946
1946
1946
1949
1949
1946
1946
1946
1946
1993
1993
1946

EndYear
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
1990
2005
2005
2005
1992
2005
2005
2005

338
339
343
344
345
346
349
350
352
355
359
360
365
366
367
368
369
370
371
372
373
375
380
385
390
395
402
404
411
420
436
432
433
434
435
437
438
439
450
451
452
461
471
475
481
482
483
484
490
500
501
510
511
516

MLT
ALB
MAC
CRO
YUG
BOS
SLV
GRC
CYP
BUL
MLD
RUM
RUS
EST
LAT
LIT
UKR
BLR
ARM
GRG
AZE
FIN
SWD
NOR
DEN
ICE
CAP
GNB
EQG
GAM
NIR
MLI
SEN
BEN
MAA
CDI
GUI
BFO
LBR
SIE
GHA
TOG
CAO
NIG
GAB
CEN
CHA
CON
DRC
UGA
KEN
TAZ
ZAN
BUI

Malta
Albania
Macedonia
Croatia
Yugoslavia (Serbia)
Bosnia-Herzegovina
Slovenia
GreeceCyprusBulgaria
Moldova
Rumania
Russia (Soviet Union)
Estonia
LatviaLithuania
UkraineBelarus
Armenia
Georgia
Azerbaijan
FinlandSwedenNorwayDenmark
IcelandCape Verde
Guinea-Bissau
Equatorial Guinea
GambiaNiger
Mali
SenegalBenin
Mauritania
Cote D’Ivoire
GuineaBurkina Faso
Liberia
Sierra Leone
Ghana
Togo
Cameroon
Nigeria
Gabon
Central African Republic
Chad
Congo
Congo, Democratic Republic of (Zaire)
UgandaKenya
Tanzania/Tanganyika
ZanzibarBurundi

1964
1946
1991
1991
1946
1992
1991
1946
1960
1946
1991
1946
1946
1991
1991
1991
1991
1991
1991
1991
1991
1946
1946
1946
1946
1946
1975
1974
1968
1965
1960
1960
1960
1960
1960
1960
1958
1960
1946
1961
1957
1960
1960
1960
1960
1960
1960
1960
1960
1962
1963
1961
1963
1962

2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
1964
2005

517
520
522
530
531
540
541
551
552
553
560
565
570
571
572
580
581
590
600
615
616
620
625
630
640
645
651
652
660
663
666
670
678
680
690
692
694
696
698
700
701
702
703
704
705
710
711
712
713
731
732
740
750
760

RWA
SOM
DJI
ETH
ERI
ANG
MZM
ZAM
ZIM
MAW
SAF
NAM
LES
BOT
SWA
MAG
COM
MAS
MOR
ALG
TUN
LIB
SUD
IRN
TUR
IRQ
EGY
SYR
LEB
JOR
ISR
SAU
YEM
YPR
KUW
BAH
QAT
UAE
OMA
AFG
TKM
TAJ
KYR
UZB
KZK
CHN
TBT
MON
TAW
PRK
ROK
JPN
IND
BHU

RwandaSomalia
Djibouti
Ethiopia
EritreaAngolaMozambiqueZambiaZimbabwe (Rhodesia)
MalawiSouth Africa
Namibia
LesothoBotswana
Swaziland
Madagascar
Comoros
Mauritius
MoroccoAlgeria
Tunisia
Libya
Sudan
Iran
Turkey/Ottoman Empire
Iraq
Egypt
Syria
LebanonJordanIsraelSaudi Arabia
Yemen (Arab Republic of Yemen)
Yemen, People's Republic of
KuwaitBahrain
Qatar
United Arab Emirates
Oman
Afghanistan
Turkmenistan
Tajikistan
Kyrgyz Republic
Uzbekistan
Kazakhstan
China
Tibet
Mongolia
TaiwanKorea, People's Republic ofKorea, Republic of
Japan
India
Bhutan

1962
1960
1977
1946
1993
1975
1975
1964
1965
1964
1946
1990
1966
1966
1968
1960
1975
1968
1956
1962
1956
1951
1956
1946
1946
1946
1946
1946
1946
1946
1948
1946
1946
1967
1961
1971
1971
1971
1946
1946
1991
1991
1991
1991
1991
1946
1946
1946
1949
1948
1948
1946
1947
1949

2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
1990
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
1950
2005
2005
2005
2005
2005
2005
2005

770
771
775
780
781
790
800
811
812
816
817
820
830
835
840
850
860
900
910
920
940
950

PAK
BNG
MYA
SRI
MAD
NEP
THI
CAM
LAO
DRV
RVN
MAL
SIN
BRU
PHI
INS
ETM
AUL
PNG
NEW
SOL
FJI

Pakistan
Bangladesh
Myanmar
Sri Lanka (Ceylon)
Maldives
Nepal
ThailandCambodia
Laos
Vietnam, Democratic Republic ofVietnam, Republic of
Malaysia
Singapore
Brunei
Philippines
Indonesia
East Timor
Australia
Papua New Guinea
New Zealand
Solomon Islands
Fiji

1947
1972
1948
1948
1965
1946
1946
1954
1954
1954
1954
1957
1965
1984
1946
1946
2002
1946
1975
1946
1978
1970

2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
1975
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005

5 References
Gleditsch, Kristian S. & Michael D. Ward, 1999. “Interstate System Membership: A Revised Listof the Independent States since 1816.” International Interactions 25: 393-413.
Gleditsch, Nils Petter; Peter Wallensteen, Mikael Eriksson, Margareta Sollenberg & Håvard
Strand, 2002. “Armed Conflict 1946-2001: A New Dataset.” Journal of Peace Research 39(5):615-637.
Harbom, Lotta & Peter Wallensteen, 2006. ”Armed Conflict, 1989–2006” Journal of Peace Research
44(5): 621-632.
Held, Birger, 1993. “Armed Conflicts over Government and Territory 1989-91” in Heldt, Birgered., States in Armed Conflict 1990-91. Uppsala: Uppsala University.
Kreutz, Joakim, 2006. “How Armed Conflicts End” Unpublished Manuscript.