UCDP Dyadic Dataset Codebook
Version 21.1
Uppsala Conflict Data Program
Department of Peace and Conflict Research
Uppsala University
Centre for the Study of Civil Wars
International Peace Research Institute, Oslo

This version compiled and updated by Therese Pettersson (2021)
When using this data, please always cite:
Harbom, Lotta, Erik Melander & Peter Wallensteen (2008) Dyadic Dimensions of Armed
Conflict, 1946-2007. Journal of Peace Research 45(5): 697-710,
Pettersson, Therese, Shawn Davis, Amber Deniz, Garoun Engström, Nanar Hawach, Stina
Högbladh, Margareta Sollenberg & Magnus Öberg (2021). Organized violence 1989-2020, witha special emphasis on Syria. Journal of Peace Research 58(4).
When appropriate, also cite this codebook: Pettersson, Therese (2021) UCDP Dyadic Dataset
Codebook v 21.1 (https://ucdp.uu.se/downloads/).
Always include the Version number in analyses using the dataset. When referring to thedataset, make sure to use the correct name: the UCDP Dyadic Dataset.

Contents
1
2

Introduction ......................................................................................................................... 3
Definition of conflict and dyad ............................................................................................. 4
2.1 Armed Conflict............................................................................................................. 4
2.2 Conflict Dyad ............................................................................................................... 5
3 Variables in the Dyadic Dataset ........................................................................................... 7
4 Additional information on variables in the dataset ............................................................ 10
4.1 Location ..................................................................................................................... 10
4.2 Incompatibility ............................................................................................................ 10
4.3 Start dates temporal precision ................................................................................... 11
4.5 System Membership Description ............................................................................... 12
5 Missing data ....................................................................................................................... 13
6 Version Name Convention ................................................................................................ 13
7 References ......................................................................................................................... 14
Appendix 1 List of System Members Since 1946 ...................................................................... 14

1 Introduction
This document describes the UCDP Dyadic Dataset, a project within the Uppsala Conflict
Data Program (UCDP), at the Department of Peace and Conflict Research, Uppsala University.
The dataset was first presented in Harbom, Melander and Wallensteen (2008) and is available
for download from http://ucdp.uu.se/downloads/.
The UCDP Dyadic dataset builds on the UCDP/PRIO Armed Conflict dataset, but goesbeyond the conflict level and focuses on dyads within each conflict. As such, it constitutes adisaggregated version of the UCDP/PRIO Armed Conflict dataset. It is compatible with arange of other datasets, both provided by UCDP and by PRIO (International Peace ResearchInstitute, Oslo).
In version 21.1, the 2020 conflicts have been added to the dataset. We refer the reader to our
Version History document for details of other changes and revisions to the dataset. The
dataset will continue to be updated annually and made available simultaneously with theupdated version of the UCDP/PRIO Armed Conflict Dataset.

2 Definition of conflict and dyad
The definition of an armed conflict is fundamental to UCDP’s data collection exercise and the
dyad is a key component of that definition. The main unit in this dataset is a “Conflict Dyad” asdefined by UCDP.1 This definition is presented unabridged in section 2.2. Each conflict dyad islisted in the database and given a unique ID code.

2.1

Armed Conflict

UCDP defines state-based armed conflict as: “a contested incompatibility that concerns
government and/or territory where the use of armed force between two parties, of which atleast one is the government of a state, results in at least 25 battle-related deaths in a calendar
year.”The separate elements of the definition are operationalized as follows:(1) Use of armed force: use of arms, 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 Item 3.3 inthis definition) in an incompatibility.2(3) Party: A government of a state or any opposition organization or alliance of organizations.
UCDP distinguishes between primary and secondary parties. Primary parties are those thatform an incompatibility by stating incompatible positions (see Item 5 in this definition). At
least one of the primary parties is the government of a state.
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.
(3.1) Government: The party controlling the capital of a state.
(3.2) Opposition organization: Any non-governmental group of people having announced aname for their group and using armed force to influence the outcome of the statedincompatibility (see Item 5 in this definition). The UCDP only deals with formallyorganized opposition. The focus is on armed conflict involving consciously
conducted and planned political campaigns rather than spontaneous violence.
(3.3) Dyad: A dyad consists of two conflicting primary parties. At least one of the primaryparties must be the government of a state. In interstate conflicts, both primaryparties are state governments. 3 In intrastate and extrasystemic conflicts, the nongovernmental primary party includes one or more opposition organization(s). A
conflict can include more than one dyad. If e.g. a government is opposed by three
rebel groups over the same incompatibility, the conflict is made up of three dyads.
1 For a more in-depth discussion on definitions, see http://www.pcr.uu.se/research/ucdp/definitions/.
2 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 oppositiongroup that caused 25 battle-deaths would be included in the dataset.
3With 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 (Section 4.1) below for further information on these cases.

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 specificterritory or an internationally unrecognised government controlling a specified territory
whose sovereignty is not disputed by another internationally recognized sovereign
government previously controlling the same territory. See section 4 for details on thesample 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 a territory,e.g. the change of the state in control of a certain territory (interstate conflict),
secession or autonomy (intrastate conflict).

2.2

Conflict Dyad

A conflict dyad is two conflicting primary parties of which at least one is the government of astate. In interstate conflicts, both primary parties are state governments. In conflict dyads inintrastate and extrasystemic conflicts, the non-governmental primary party is an organised
opposition organisation.
The separate elements of the definition are operationalized as follows:
1) Primary parties: The parties that form the incompatibility by stating incompatible
positions. The incompatibility (i.e. the conflict issue) must concern governmental power(type of political system, the replacement of the central government or the change ofits composition), territory (the status of a territory, e.g. the change of the state incontrol of a certain territory - interstate conflict - secession or autonomy - intrastate
conflict) or both.
2) Government: The party controlling the capital of a state.
3) 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 fordetails on the sample of countries covered by this definition.
4) Opposition organization: Any non-governmental group of people having announced aname for their group and using armed force to influence the outcome of the statedincompatibility. The UCDP only deals with formally organized opposition. The focus ison armed conflict involving consciously conducted and planned political campaigns
rather than spontaneous violence.
To differentiate between dyads is at times problematic. When is a dyad completely new andwhen is it simply a continuation of an already registered dyad, only slightly altered? The key

difficulty here is to distinguish between opposition organisations, as the other primary party inthe dyad – the government of a state – never changes.4 Some opposition groups tend to be
fractious, splitting into different sub-groups while others join larger coalitions or umbrellagroups. UCDP follows four main rules:● However many times a group changes its name, it still retains the same dyad_id (forexceptions, see below).
● When a group splits, the splinter group is considered a completely new opposition
organisation, and if it continues opposing the government and all other criteria are
fulfilled, it constitutes part of a new dyad in the dataset, with a new dyad_id.
Comment: It is sometimes difficult to determine which of the groups should be viewed
as the splinter and which should be seen as the original group, as both fractions tend toclaim to be the “real” rebel group. UCDP deals with this by tracing the main part (i.e.
the most numerous) of the group, which is then coded as the original one. Should thisbe problematic to determine, a second option is to trace the original leader of thegroup in order to identify the original opposition organisation.
● When two or more already registered groups join together under a new name in a tightcoalition with joint military operations, the new coalition is regarded as a new
opposition organisation. If it continues to oppose the government and if all othercriteria are fulfilled, it is included as part of a new dyad in the dataset, and given a new
dyad_id.
● When an already registered group is joined by another group that has previously not
been coded as active in the dataset, the opposition organisation is viewed as acontinuation of the former. This applies even when the name of the group is changed.
Comment: It should be noted that while this rule is applied in most cases in the dataset
conventional logic made it necessary to make some exceptions. Whereas the rule
works well in e.g. the case of NRA in Uganda, which was originally called PRA, butchanged its name when it was joined by the much smaller and militarily insignificant UFF,
the logic is less clear in the case of e.g. the Independent Nasserist Organisation in
Lebanon (a.k.a. al-Mourabitoun), which was active in fighting the government of
Lebanon in 1958 and also resurfaced as part of the Lebanese National Movement in
1975. In this case, it is intuitively and factually incorrect to characterise the LNM as
being a simple continuation of al-Mourabitoun, and the dyad is thus characterised as
being an entirely new one.

4 By this, we mean that while the party in control of the government may change it is still viewed as one and the same party in the dataset.

3 Variables in the Dyadic Dataset
The observation (or unit) in the Main Conflict table is the dyad-year. Each dyad is listed in all
years where fighting caused at least 25 battle-related deaths.
The calendar year is the basic unit of every observation. Thus, if fighting in a dyad during theperiod June–September results in 30 casualties, the dyad will be considered active and will thus
be included in the dataset However, if the same number of casualties occurred in the period
November–February and fighting in the dyad failed to reach the threshold of 25 battle-related
deaths in either calendar year, the dyad will not be coded as active in either year. This has anumber of consequences that will be discussed below. Start dates frequently refer to years
prior to the first calendar year of dyad activity, as the start of a conflict might be in a year withless than 25 casualties. Certain observations might be based on a single event, such as theOmagh bombing in Northern Ireland in 1998, which exceeded the minimum threshold forarmed conflict.
Variable nameContent

Type

dyad_id

The unique identifier of the dyad.

Integerconflict_id

The unique identifier of the conflict to which the dyad
corresponds, as given in the UCDP/PRIO Armed
Conflict Dataset version 21.1

Integer

location

The name of the country/countries whose
government(s) has a primary claim to the incompatibility,
Note that this is not necessarily the geographical locationof the conflict. Further information on how location isinterpreted can be found below, in section 4.1.
If multiple countries are listed, this is comma separated.

Stringside_aThe name of the country/countries of Side A in a conflict.
Always the government side in intrastate conflicts. Notethat this is a primary party to the conflict.

Stringside_a_id

The unique identifier of the actor on side A.

Integer

Note that in contrast with older versions of UCDP
datasets, this variable is NO LONGER the Gleditsch andWard state identifier (GWcode or GWNo). Use thegwno_a variable instead.
side_a_2nd

side_a_2nd lists all states that enter a conflict dyad withtroops to actively support side A. By definition, only
independent states can be a secondary party in conflict.
A secondary warring party on side A shares the positionin the incompatibility with Side A in the conflict.
Side_a_2nd does not need to meet the 25 battle-related
deaths criterion to be included in the dataset; an active
troop participation is enough.

StringComma separated if multiple.
side_b

Identifying the opposition actor or country of side B in the
dyad. In an intrastate conflict, this includes a militaryopposition organization. Note that this is a primary party
to the conflict.

Stringside_b_id

The unique identifier of the actor on side B in the dyad.

StringNote that in contrast with older versions of UCDP
datasets, this variable is NO LONGER the Gleditsch andWard state identifier (GWcode or GWNo) if the conflictis interstate and Side B represents a country. Use thegwno_b variable instead.
side_b_2nd

side_b_2nd lists all states that enter a conflict dyad withtroops to actively support side B. By definition, only
independent states can be a secondary party in conflict.

StringA secondary warring party on side B shares the positionin the incompatibility with Side B in the conflict.
Side_b_2nd does not need to meet the 25 battle-related
deaths criterion to be included in the dataset; an active
troop participation is enough.
Comma separated if multiple.
incompatibility

The main conflict issue identified per the UCDP
definitions, as applied to the dyad:
1= Incompatibility about territory
2= Incompatibility about government
3= Incompatibility about government AND territory
Further information on how incompatibility is interpreted
can be found below, in section 4.2

Integer

territory_name

The name of the territory over which the conflict isfought, provided that the incompatibility is over territory.
In case the two sides use different names for the disputed
territory, the name listed is the one used by the
opposition organization. One reason for this is that this ismost often the name that the general public recognizes.
Another reason is that there are cases where thedisputed territories do not have an official name.

Stringyear

The year of observation (1946-2020).

Integerintensity_level

The intensity level in the dyad per calendar year. The
Integerintensity variable is coded in two categories:5
1. Minor: between 25 and 999 battle-related deaths in

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

a given year.
2. War: at least 1,000 battle-related deaths in a given
year.
type_of_conflict

One of the following four types of conflict that the dyad is
active in:

Integer

1 = extrasystemic (between a state and a non-state groupoutside its own territory, where the government side isfighting to retain control of a territory outside the statesystem).
2 = interstate (both sides are states in the Gleditsch andWard membership system).
3 = intrastate (side A is always a government; side B isalways a rebel group; there is no involvement of foreign
governments with troops, i.e. there is no side_a_2nd or
side_b_2nd coded).
4 = internationalized intrastate (side A is always agovernment; side B is always a rebel
group; there is involvement of foreign
governments with troops, i.e. there is at least ONE
side_a_2nd or side_b_2nd coded).
start_date

The date, as precise as possible, of the first battle-related
death in the dyad.
The date is set after the dyad fulfils all criteria required in
the definition of an armed conflict, except for the numberof deaths.6

Datestart_prec

The level of precision for the initial start date.
The values are explained in section 4.3

Integerstart_date2

The date, as precise as possible, when fighting in the dyad
in a given episode of conflict activity reached 25 battlerelated deaths in a year. Thus, for each episode of aconflict dyad, a new start_date2 is coded. In case precise
information is lacking, start_date2 is by default set to 31
December.
An episode is defined as continuous conflict activity.
Consequently, a new episode is coded whenever a dyad
restarts after one or more year(s) of inactivity.

Datestart_prec2

The level of precision for startdate2.
The values are explained in section 4.3

Integer

gwno_aThe Gleditsch and Ward country codes of side_a.
Comma separated if multiple.

Stringgwno_a_2nd

The Gleditsch and Ward country codes of side_a_2nd.
Comma separated if multiple.

String(YYYY-MM-DD)(YYYY-MM-DD)

6 In some cases, the initial fatality occurs in a year prior to the first year of activity. For instance, in the conflict in Ethiopia over the territory

Eritrea (conflict ID 275), the first battle-related deaths occurred in September 1961. During the remaining months of 1961, the conflict did notreach the required 25 battle-related deaths threshold and the conflict is thus coded as inactive in 1961. 25 battle-related deaths were notrecorded until three years later.

gwno_b

The Gleditsch and Ward country codes of side_b.
Comma separated if multiple.

Stringgwno_b_2nd

The Gleditsch and Ward country codes of side_b_2nd.
Comma separated if multiple.

Stringgwno_loc

The Gleditsch and Ward country codes of theincompatibility.
Comma separated if multiple.

StringregionThe region of the incompatibility:
1 = Europe (GWNo: 200-399)
2= Middle East (GWNo: 630-699)
3= Asia (GWNo: 700-999)
4= Africa (GWNo: 400-626)
5= Americas (GWNo: 2-199).

StringversionThe version of the dataset: 21.1

Float

4 Additional information on variables in the dataset
4.1

Location

Location is defined as the government side in a dyad, and should not be interpreted as thegeographical location of the conflict.
-

-

4.2

For dyads in intrastate and internationalized intrastate conflicts, only one country nameis listed. This is the country whose government is disputed.
In most interstate conflicts only one dyad, i.e. two states, is active and both theseprimary parties are listed in the Location filed. Even when several governments are
involved in a conflict, these are all included as the same dyad in this version of thedataset.7 Subsequently, in these few cases all parties are listed in the location filed.
For dyads in extrasystemic conflicts, Location is set to be the disputed area, not the
government of the colonial power. Thus, in these conflicts the Location filed by default
does not indicate members of the international system.

Incompatibility

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. The incompatibility is coded in three categories:

7 There are four cases in the dataset where there are more than two primary parties active in a conflict between states. These are the Arab-

Israeli war of 1948-49, the Suez war of 1956, the war in Afghanistan in 2001 and the war in Iraq in 2003.

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, thestated incompatibility 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. Furthermore, as each conflict
can involve more than one dyad, the state can simultaneously be involved in several dyads inextrasystemic- as well as intrastate conflicts.

4.3

Start dates temporal precision8

The start_date is coded as precisely as possible. For certain dyads we can pinpoint the start of
the armed conflict down to a single event, taking place on a specific day. For other dyads, thisis not possible, due to lack of precise information. The start_prec (start precision) is coded tohighlight the level of certainty for the date set in the start_date 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 of several 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 occurred on different dates.
3. Day is unknown; month (or a period of 30 days, not necessarily a calendar month) andyear are precisely coded. The day is known to be in a given month or 30 day-period, but
we are missing information on an exact date. Day is then set to the last day of the period.
4. Month is assigned; year is coded precisely.
5. Day and month are unknown, year is coded precisely. Day and month are set as
precisely as possible. For example, if an event is known to have taken place sometime
between January and August, the date is coded as 31 August of the coded year, with a
precision of 5.
6. Year is assigned. There is a wide disagreement between different sources, so that noteven year can be coded precisely. The start year is assigned based on subjective
judgment. Day and month are set as precisely as possible. For example, if an event is
known to have taken place sometime between January and August in an assigned year,
the date is coded as 31 August, with a precision of 6.
7. Year is missing. No reliable information on the start year is available. Day and month
are set as precisely as possible for the first year of recorded activity. For example, if an
event is known to have taken place sometime between January and August in an
assigned year, the date is coded as 31 August, with a precision of 7.

8 The format for coding start dates has been slightly changed in 2014, and then again in 2017, in an attempt to provide more detailed

information.

Note: If the dyad was active (i.e. fulfilled all inclusion criteria) before 1946, start_date2 is set to
1 January of 1946 and start_prec2 is given the precision score 7.

4.5

System Membership Description

The definition of a state is crucial to the UCDP/PRIO conflict list, and subsequently also forthe dyadic dataset. 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, and hence also the dyad 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 (2007) systems membership definition, which is based on the Correlatesof 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 sizeof 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 themultinational coalition fighting in Iraq in 2004.
The UCDP/PRIO dataset includes one political entity that lacks a country code (gwno_a 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
system membership 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 couple of cases, the dataset has 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)

Georgia:
Gleditsch & Ward: 6 September 1991 (the USSR’s recognition of Georgia’s declarationof independence, on 9 April 1991)
UCDP/PRIO: 21 December 1991 (USSR formally ceased to exist)
Comment: While Gleditsch & Ward claim that the USSR recognized Georgia’s
independence on 6 September, this seems to be incorrect. On 6 September, the Soviet
Union recognized the Baltic States’ independence, but not Georgia’s. Instead, the Soviet
Union in early September 1991 refused to discuss recognition of the declaration of
independence.

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
based on Gleditsch & Ward’s 2013 version of the list of independent state.

5 Missing data
The missing data code is -99. However, the dataset does not include unclear conflicts where
information on key variables to the definition of conflict and dyad is uncertain or missing. Keyvariables are those related to the incompatibility, actors and intensity. In addition, a number of
events have been 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 for further 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 4.3. Apart from that, the dataset only
includes information when we are quite confident that it is correct. The bias produced by thisapproach is against the inclusion of conflicts in the earlier decades and in the less-developed
world. An armed conflict in a developed country in the 1990s is more likely to be recorded
than a conflict in a less developed country in the 1950s.

6 Version Name Convention
In 2017, the version name convention was changed, giving all UCDP datasets the same version
number across the board. This was done so that users more easily can see which UCDP
dataset corresponds with which.
This codebook corresponds to Version 21.1 of the UCDP Dyadic Dataset. For every new
release, substantial changes will be documented in a separate document. This should be helpful
to researchers trying to replicate a particular study. We recommend that whenever thisdataset is used, the version number should be cited.
The version number is a combination of a year and a number. The year refers to when thedataset is updated with new observations. If there are changes in the data between yearlyupdates, or if there are substantial changes in the structure of the dataset, the number behindthe year is incremented.

7 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, Kristian S. Skrede & Michael D. Ward (2013) System membership case description
list.
Harbom, Lotta, Erik Melander & Peter Wallensteen (2008) Dyadic Dimensions of Armed
Conflict, 1946-2007. Journal of Peace Research 45(5): 697-710
Pettersson, Therese, Shawn Davis, Amber Deniz, Garoun Engström, Nanar Hawach, Stina
Högbladh, Margareta Sollenberg & Magnus Öberg (2021). Organized violence 1989-2020, witha special emphasis on Syria. Journal of Peace Research 58(4).

Appendix 1 List of System Members Since 1946
StateNum

StateAb StateName

StartYear

2
20
31
40
41
42
51
52
53
70
80
90
91
92
93
94
95
100
101
110
115
130
135
140
145
150
155
160

USA
CAN
BHM
CUB
HAI
DOM
JAM
TRI
BAR
MEX
BLZ
GUA
HON
SAL
NIC
COS
PAN
COL
VEN
GUY
SUR
ECU
PER
BRA
BOL
PAR
CHL
ARG

1946
1946
1973
1946
1946
1946
1962
1962
1966
1946
1981
1946
1946
1946
1946
1946
1946
1946
1946
1966
1975
1946
1946
1946
1946
1946
1946
1946

United States of America
CanadaBahamasCuba
Haiti
Dominican Republic
Jamaica
Trinidad and Tobago
Barbados
MexicoBelizeGuatemalaHonduras
El Salvador
Nicaragua
Costa Rica
PanamaColombia
Venezuela
GuyanaSurinamEcuador
Peru
BrazilBoliviaParaguay
Chile
Argentina

EndYearStateNum

StateAb StateName

StartYear

165
200
205
210
211
212
220
225
230
235
260
265
290
305
310
315
316
317
325
338
339
340
341
343
344
345
346
347
349
350
352
355
359
360
365
366
367
368
369
370
371
372
373
375
380
385
390
395
402

URU
UKG
IRE
NTH
BEL
LUX
FRN
SWZ
SPN
POR
GFR
GDR
POL
AUS
HUN
CZE
CZR
SLO
ITA
MLT
ALB
SER
MNG
MAC
CRO
YUG
BOS
KOS
SLV
GRC
CYP
BUL
MLD
RUM
RUS
EST
LAT
LIT
UKR
BLR
ARM
GRG
AZE
FIN
SWD
NOR
DEN
ICE
CAP

1946
1946
1946
1946
1946
1946
1946
1946
1946
1946
1949
1949
1946
1946
1946
1946
1993
1993
1946
1964
1946
2006
2006
1991
1991
1946
1992
2008
1992
1946
1960
1946
1991
1946
1946
1991
1991
1991
1991
1991
1991
1991
1991
1946
1946
1946
1946
1946
1975

Uruguay
United Kingdom
IrelandNetherlands
Belgium
Luxembourg
FranceSwitzerland
Spain
Portugal
German Federal Republic
German Democratic Republic
PolandAustria
Hungary
Czechoslovakia
Czech Republic
Slovakia
Italy/Sardinia
Malta
Albania
SerbiaMontenegro
Macedonia (FRY)
Croatia
Yugoslavia (Serbia)
Bosnia-Herzegovina
KosovoSlovenia
GreeceCyprusBulgaria
Moldova
Rumania
Russia (Soviet Union)
Estonia
LatviaLithuania
UkraineBelarus (Byelorussia)
Armenia
Georgia
Azerbaijan
FinlandSwedenNorwayDenmark
IcelandCape Verde

EndYear

1990

1992

2006

StateNum

StateAb StateName

StartYear

404
411
420
432
433
434
435
436
437
438
439
450
451
452
461
471
475
481
482
483
484
490

GNB
EQG
GAM
MLI
SEN
BEN
MAA
NIR
CDI
GUI
BFO
LBR
SIE
GHA
TOG
CAO
NIG
GAB
CEN
CHA
CON
DRC

1974
1968
1965
1960
1960
1960
1960
1960
1960
1958
1960
1946
1961
1957
1960
1960
1960
1960
1960
1960
1960
1960

500
501
510
511
516
517
520
522
530
531
540
541
551
552
553
560
565
570
571
572
580
581
590
600
615
616

UGA
KEN
TAZ
ZAN
BUI
RWA
SOM
DJI
ETH
ERI
ANG
MZM
ZAM
ZIM
MAW
SAF
NAM
LES
BOT
SWA
MAG
COM
MAS
MOR
ALG
TUN

Guinea-Bissau
Equatorial Guinea
GambiaMali
SenegalBenin
Mauritania
Niger
Cote D’Ivoire
GuineaBurkina Faso (Upper Volta)
Liberia
Sierra Leone
Ghana
Togo
Cameroon
Nigeria
Gabon
Central African Republic
Chad
Congo
Congo, Democratic Republic of(Zaire)UgandaKenya
Tanzania/Tanganyika
ZanzibarBurundiRwandaSomalia
Djibouti
Ethiopia
EritreaAngolaMozambiqueZambiaZimbabwe (Rhodesia)
MalawiSouth Africa
Namibia
LesothoBotswana
Swaziland
Madagascar (Malagasy)
Comoros
Mauritius
MoroccoAlgeria
Tunisia

1962
1963
1961
1963
1962
1962
1960
1977
1946
1993
1975
1975
1964
1965
1964
1946
1990
1966
1966
1968
1960
1975
1968
1956
1962
1956

EndYear1964

StateNum

StateAb StateName

StartYear

620
625
626
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
770
771
775
780
781
790
800
811
812
816
817
820
830
835
840

LIB
SUD
SSD
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
PAK
BNG
MYA
SRI
MAD
NEP
THI
CAM
LAO
DRV
RVN
MAL
SIN
BRU
PHI

1951
1956
2011
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
1947
1971
1948
1948
1965
1946
1946
1953
1954
1954
1954
1957
1965
1984
1946

Libya
Sudan
South Sudan
Iran (Persia)
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
Taiwan
North Korea
South Korea
Japan
India
BhutanPakistan
Bangladesh
Myanmar (Burma)
Sri Lanka
Maldives
Nepal
ThailandCambodia (Kampuchea)
Laos
Vietnam, Democratic Republic ofVietnam, Republic of
Malaysia
Singapore
Brunei
Philippines

EndYear

1990

1950

1975

StateNum

StateAb StateName

StartYear

850
860
900
910
920
940
950

INS
ETM
AUL
PNG
NEW
SOL
FJI

1946
2002
1946
1975
1946
1978
1970

Indonesia
East Timor
Australia
Papua New Guinea
New Zealand
Solomon Islands
Fiji

EndYear