Timeline 800-825 (Interference)

== 801-805 ==
I'll try to further simplify things by putting "territorial markers" before news for each year. But beware: events can not be too neatly labeled that way.
801
Western Europe:
The Treaty of Weissenburg carves the HRCEW between Charles’s three “legitimate” sons: Charles II the German, the elder son, receives East Francia (Germany), Bavaria and the imperial title, Theodoric/Pepin obtains the lands from Frisia to Aquitaine and Louis the Pious Burgundy, Provence, Septimania. The three brothers then strike a deal to jointly attack Pepin the Hunchback “to free the Papacy and avenge our beloved father”
802
Western Europe:
When his half-brothers move against him appearing in Italy, Pepin II the Hunchback is lynched by a mob in Rome; Charles II, there after, is crowned in St. Peter in the presence of his brothers, not before humiliating and deposing Pope Leo III for crowning his father’s assassin, and replacing him with the Irish St. Cassian of Hibernia, the most brilliant scholar of the Carolingian court, who takes the name of Patricius. Salerno and Taranto, now both reduced to Duchies, are entrusted to Frankish dukes loyal to Charles II. The Venet(ic)ians, led by their Doge John Galbaius, sack Grado and kill Patriarch John.
British Isles:
The Norwegian Vikings sack and destroy the great Irish abbey of Iona, in the Hebrides. Anglo-Saxon Wiccia (Hwicce) is finally annexed to Mercia.
Byzantine Empire:
The Byzantine general Bardanes the Turk, an important strategos (theme governor) in Anatolia, rebels in support of iconoclasm and against the “Syracusan Iconophile usurper” Marcianus II Bulla and actually deprives Byzantium of control over its main Asian stronghold.
SE Asia:
King Jayavarman II of upper Chenla, grown at the Srivijayan court, frees the Khmers and the Mekong delta region from Srivijaya and founds the new kingdom of Kambuja, holding sway over Laos, Siam, Cambodia and Cochinchina
803
Byzantine Empire: 
Marcianus II Bulla attacks Bardanes the Turk in Anatolia but is routed at the battle of Dadastana; hunted by the winner, Marcianus flees back first to Athens, thence to Syracuse, and the Byzantine Empire is anew divided.
Western Europe:
Charles II and Liutpert of (northern) Lombardy make Friul a March and occupy Dalmatia taking advantage of Byzantine weakness.
Central-Eastern Europe:
After wresting the region between the Tisza and Transylvania from the crumbling Avars, the fierce Krum, lord of the Pannonian Onogurs and a scion of the Dulo clan, ascends the throne of Bulgaria: his kingdom stretches from the middle Danube to the Black Sea.
India:
Govinda III Rashtrakuta defeats and vassalizes an alliance of Pallava, Pandya, Chera and Ganga forces in SE Deccan; his younger brother Indra founds a second Rashtrakuta dynasty in Gujarat
804
Central-Eastern Europe:
A joint action between Charles II the German and Khan Krum of Bulgaria crushes the Avars in Pannonia; the Bulgarians gain vast swaths of land in Dacia and Pannonia, the surviving Avar are vassals to the HRCEW.
Byzantine Empire: 
A new council summoned in Chalcedon by basileus Bardanes reimposes Iconoclasm, supported by most of the army, in the eastern Byzantine empire.
Caucasus:
After long struggles Ashot I Bagratuni nicknamed the Carnivore, king of Iberia/Georgia, is able to take over also the throne of Armenia (as Ashot III); he rebels against Abbasid suzerainty with eastern Byzantine support, but can not take Tbilisi (where a Caliphal emir rules) and break ties with Baghdad
805
Western Europe:
King Godfred’s Danes repel a Frankish invasion led by HRCEW Charles II; in the campaign an Indian war elephant, a kind present of the Abassid Caliph Harun ar-Rashid, is used, but to no avail, then Godfred is killed by his men and order on the border is restored.
British Isles:
The Celtic kingdom of Strathclyde annexes North Rheged through dynastic ties.
Central-Eastern Europe:
The Avar Khan Zodan, vassal to the Franks, receives baptism with the name of Theodore.
Middle East:
Harun ar-Rashid manages to newly subdue the rebellious Daylamites of N. Persia.
Summary: western Byzantium crumbles, crushed between the Idrisids and the Carolingians. Eastern Byzantium continues to suffer from lack of an enduring competent leadership. The Holy Roman Catholic Empire of the West is, as usual, a nest of vipers.
== 806-810 ==
806
North Africa:
Marcianus II Bulla lands in Ifrigia (*OTL Tunisia) to confront the marauding Idrisids from Tripolitania, but is trounced and killed by the Muslim invaders at St. Maximus oasis in the south; the Idrisids then assault, take and raze Carthage to the ground, while the Primate of Africa, archbishop Maximus IV, takes refuge in Sicily, where a succession war quickly begins. A massive flow of refugees flees to Numidia. Peter the Brigand, a Berber chieftain of the western Atlas, conquers Tlemsen (Numidia) from Mauretania with support from Visigothic mercenaries, and founds a kingdom centered on that city
806-808
Byzantine Empire:
Abbasid forces invade and overrun most of Anatolia, conquering key fortresses like Angora and Amorion and extracting renewed tribute from Byzantium
807
Southern Europe:
In Sicily the legitimists rally in Syracuse behind empress Euphemia and the five-years-old Constantia, while the pretenders Augustin of Malta and John Chrisostratos vie for supremacy in most of the island.
Byzantine Empire:
An Abbasid fleet plunders Rhodes. The Slavs of Peloponnesus/Morea besiege Patras, but are wholly defeated and subdued by eastern Byzantine forces
808
North Africa:
The Shi'ite Caliph of Tripolitania and Ifrigia (*OTL Tunisia) Idris II founds Tunis near the ruins of Carthage.
Southern Europe:
Frankish and Lombard forces led by emperor Charles II take Calabria, land in Sicily and crush the two pretenders to the Western Byzantine crown, then force the submission of Syracuse. Sicily, deprived of Calabria attached to the Duchy of Salerno, of Corsica attached to the (nominally Lombard) Duchy of Tuscany and of Sardinia left to cope for herself, becomes a vassal kingdom of the HRCEW, where the eleven year old Leo, son of the defunct Constantine VI of Byzantium and nephew of Charles II, will reign by marrying little Constantia Bulla: the Western Byzantine empire doesn’t exist anymore. The Papacy assumes a theoretical suzerainty over Corsica and Sardinia; in the latter, the western Byzantines had organized the four “judicates” (local provinces) of Gallura, Torres, Cagliari and Arborea.
Byzantine Empire:
Paulician revolt led by Arsaviros between Anatolia and Armenia; basileus Bardanes crushes the rebels
809
Byzantine Empire:
The Bulgarian Khan, Krum, routs the Byzantine army on the Struma, killing basileus Bardanes (with whose skull he makes a cup) and conquers Serdica/Sofia, the last Byzantine stronghold in the Sklaviniai (*OTL Balkans); in Constantinople, after a brief struggle, general Leo V the Armenian (an Anatolic Mardaite, actually) has himself crowned
809-813
Middle East:
In the Abbasid Caliphate the death of Harun ar-Rashid is followed by a succession war between his sons al-Amin and al-Ma’mun: the latter, based at Marv (Khorasan), prevails
810
North Africa:
The Idrisid Arabs invade Numidia and subdue several towns and tribes in the country, despite a heavy resistance.
Western Europe:
Theodoric/Pipin dies, leaving his part of the HRCEW (from Frisia to northern France and Aquitaine) to the 13 year old son Bernard; the Bretons take the opportunity to break free from Frankish control, while the Danes invade and conquer most of Frisia; Charles II, ill, can’t intervene; Louis the Pious does nothing to help
ca. 810
Far East:
The Japanese complete the submission of the Ainus in northern Honshu.
Northern Europe:
The Norwegian Vikings conquer the Alban Isles (*TTL colective name for Shetlands, Orkneys, Hebrides).
Western Europe:
The work of Pope Patricius (St. Cassian of Hibernia), who’ll be hailed as the last great Father of the Catholic Church, encourages the use of local languages in the Christian liturgy; in the centuries, first the prayers, then the very holy texts will be translated. Foundation of the HRCEW march of Vasconia/Navarra under duke Adalric of Gascony
== 811-815 ==
Summary: the HRCEW shows all the frailty of Frankish succession laws and feudalism, Byzantium regains a minimum of strength, the Abbasids vie for power
811
Western Europe:
HRCEW Charles II the German dies while his son Roland is still in his teens; in the Diet of Metz, Louis the Pious enforces the system of the Majorate for the governance of the Empire (the older member of the family is crowned as emperor, no matter who was the emperor before) and has himself crowned and anointed in Rome in the place of young Roland
812
Byzantine Empire:
Khan Krum’s Bulgarians are repelled by Leo V after a most heavy siege of Adrianople and the devastation of Thrace.
North Africa:
Helped by Fredegarius’ Visigoths, the Numidians led by Peter the Brigand decisively stem the Idrisid Arab invaders, then, on the site of the battle, they found Kabylonica (*OTL Algiers).
Western Europe:
Foundation of the Frankish county of the Razès/Rennes-le-Chateau (between Carcassonne and the Pyrenees), a former Visigothic border stronghold. Brittany is again reduced to obedience by the Frankish armies.
British Isles:
Essex is vassalized by Mercia, which in turn loses suzerainty over Sussex in favor of Wessex
813
Byzantine Empire:
Krum directly tries to assault Constantinople’s wall with a large horde of Slavs, Avars and Bulgarians, but fails miserably and withdraws home.
Western Europe:
Duke Bernard of Septimania, a Jew, converts to confirm his loyalty to Louis the Pious, who is an ardent Catholic
813-826
Middle East:
Revolt by Nasr in northern Syria and Cilicia; in the end he is captured and executed by the Abbasid Caliph al-Ma’mun
814
Byzantine Empire:
Just after Krum’s death the Bulgarians are overrun by basileus Leo V at Burtudizos (Thrace).
Western Europe:
The Council of Tours, held under the auspices of Pope Patricius (St. Cassian of Hibernia), invites the Catholic clergy to preach in the vernacular languages of Europe and North Africa (“rusticam romanam linguam”) rather than in Latin. The Venet(ic)ians move their capital from Methamaucus to the lagoon islets of Rialto: in time, the city will be called Venice.
814-815
Middle East:
Great revolt led by Abu Saraya in Kufa and Basra; when it threatens Baghdad, general Harthama crushes the rebels
ca. 815
Northern Europe:
The Yngling clan (the ruling dynasty of Vestfold) ascends the throne of Sogn in central Norway with Harald Goldbeard.
Byzantine Empire:
The Iconoclastic issue again heats the climate in Constantinople, with the monk Theodore of Studium leading the Orthodox (icon-worshipping) front.
North Africa:
The Idrisids win the favor of the local Kharijite tribes and wrest Cyrenaica from Omayyad Egypt
== 816-820 ==
816-838
Caucasus:
The great Zoroastrian uprising led by Babak in Azerbaigian shatters the kingdom of Caucasian Albania, a client of the Abbasids of Baghdad but still formally Christian; Babak creates an ephemeral but strong theocratic empire based on Mazdakism but also open to Manichaean and even Hindu influences; its very existence fosters the rise of a militant Paulicianism in Cappadocia
817
Western Europe:
At the Diet of Aquisgrana/Aachen the HRCEW Louis the Pious determines that his eldest son, Lothar, being some weeks older than Roland, has to be his successor as emperor; he also entrusts Bavaria and Aquitaine respectively to his sons Louis II and Pipin III, both with royal title, setting the countdown for the feudal implosion of the HRCEW. Roland and Bernard refuse to accept this arrangement and prepare for the inevitable clash.
Middle East:
To quell the unrest among the Shi'ites, the Abbasid Caliph of Baghdad al-Ma’mun appoints as successor the eighth Shi’a Imam, Alì al-Rida, who a few months thereafter dies, likely poisoned.
817-819
Middle East:
The disturbances in the Abbasid Caliphate reach a new heighth with the usurpation by Ibrahim al-Mubarak (a mixed-blood son of an African slave girl) in Baghdad, then al-Ma’mun retakes power and finally moves to Baghdad from his former capital at Marv. The Egyptian Omayyads of Caliph al-Hakam I, though, take advantage to conquer Palestine with Jerusalem and obtain the submission of the Holy Places of Islam in the Hijaz (Mecca and Medina)
818-819
Western Europe:
Louis the Pious defeats his nephews Roland and Bernard one at a time, respectively in the battle on the Sieg river (Westfalia) and at Arlon (Belgium). Bernard flees to Wessex, while Roland takes refuge among the Pannonian Slavs; their ban (duke) Ljudevit Posavski, then tries to bring back Roland in Italy, annihilating Carantania/Koroška on his way; he also invades and ravages Friul. Roland tries to reach Rome and his allies in the south of Italy but is killed by the Lombards at Florence, leaving Louis only emperor of the Holy Roman Catholic Empire of the West. Meantime the marquis of Friul, Cadolaus, beats back Ljudevit’s horde beyond the Alps
818-821
Central-Eastern Europe:
The Sklavinian (*OTL Balkan) Bulgarians conquer southwestern Ukraine defeating Slavs and Magyars up to Kiev
819
Western Europe:
Oliba I, son of count Borrell/Bellon, founds the county of Carcassonne.
Arabia:
Zaydi Yemen gains de facto independence from the Abbasid Caliphate
819-823
Central-Eastern Europe:
Ljudevit Posavski puts up a gallant defence of Slavic Pannonia (Croatia and Hungary west of the Danube), but in the end he is defeated and flees through Serbia; his uncle, Borna, ban of the Slavs of Liburnia and Dalmatia, jails and kills him to please the Franks.
Western Europe:
After the Papacy mediates to avoid bloodshed in Italy, Louis the Pious has to pardon the two former Rolandist dukes of Salerno and Taranto, Adalgerius and Hermann. Roland’s and Bernard’s infant sons, Pepin and the illegitimate Odoacer, are held in Louis’ court at Aquisgrana/Aachen
820
North Africa:
After mustering a strong fleet, king Leo of Sicily sails to Africa, but fails in the siege of Tunis and withdraws.
Byzantine Empire:
Basileus Leo V the Armenian foils a plot to overthrow him and kills the rebel leader, general Michael of Amorion.
Hesperia (*OTL America):
The line of kings in Xukpi/Copàn comes to an end; this Mayan city-State crumbles and is abandoned in less than ten years
ca. 820
Byzantine Empire:
The Byzantines reassert their control over the inner mountain region east of Dyrrachium and Valona, where the resistance of the Illyrians to the Slavs is resulting in the birth of the Albanian people.
Western Europe:
In the HRCEW Louis the Pious bestows even greater power on the Roman Church and local abbeys
== 821-825 ==
Summary: Carolingian consolidation in the West, Byzantium suffers a revolution, Wessex gains paramountry in England.
820-835
Middle-East:
Southern Iraq is shaken by the long rebellion of the Zotts, a people partly deported by the Arabs from NW India, where they were known as Jats
British Isles:
Fierce Viking raids on Western Scotland and Alba force king Angus II of Dalriada and Alba to move his capital east from Argyll
821
Central Asia:
Tahir ibn al-Husayn, governor of Baghdad and strongman of the Abbasid Caliphate, de facto carves an own State in Khorasan and northern Afghanistan with capital at Nishapur and founds the Tahirid dynasts
821-823
Byzantine Empire:
A huge revolt based on ethnic, social and religious issues (contact with Babakist/Mazdakist rebels in Azerbaigian is proved) erupts in Anatolia, led by Thomas the Slav and heartily supported by both the peasantry and the Abbasid Caliph al-Ma’mun; Constantinople suffers two long years of siege, then, when Bulgarian khan Omurtag too overtly sides with the rebels, the imperial fleet mutinies and kills basileus Leo V; Thomas is hailed as the new ruler and pays tribute to Bulgaria
822
Central Asia:
Abbasid (Tahirid) forces finally complete the conquest of Central Asia by vassalizing the kingdom of Usrushana in the Chach/Tashkent), where Islam begins to spread.
British Isles:
Bernard is killed in Wessex upon orders of king Egbert, eager to appease Louis the Pious
822-826
Western Europe:
After another long and bloody civil war (not without Maurian, Frankish, Gallastrian and even Viking encroachments) Roderic II, Fredegarius’ nephew, ascends the Visigothic throne of Spain in Toledo and ensures dynastical continuity to the kingdom, partially reforming it according to the feudal Frankish model
823
British Isles:
Cyngen ap Cadell of North Powys repel a major Mercian invasion of Wales at the battle of Powys Castle.
Southern Europe:
The town of Gaeta, on the border between the Papal lands and the Duchy of Salerno, gains de facto independence
824
Caucasus:
Ashot III Bagratuni the Carnivore, ruler of Armenia and Iberia/Georgia, dies. Armenia is divided between his sons Smbat III the Confessor, who gets most of the country, and Bagrat I, who gets the principality of Taron replacing the local Mamikonian rulers; after six years Bagrat I will also gain the Iberian/Georgian crown
North Africa:
The Idrisids of Tunis and Libya conquer Malta, then stage an invasion of Omayyad Egypt which is utterly repulsed at el-Daba
825
British Isles:
King Egbert’s Wessex Saxons first suffer a defeat at Galford against the Cornish, then, in alliance with the Welsh kingdoms, gain a most great victory over Mercia at Ellandon and proceed to annex Essex and Kent.
SE Asia:
Thmala founds the Mon kingdom of Pegu (southern Burma)
ca. 825
Central-Eastern Europe:
the Magyars vassalize the Onoguro-Bulgarians of Taurida (*OTL Crimea). Rise of the Greater Moravian empire north of Slavic Pannonia.
North Africa:
The Idrisids gain an effective supremacy over eastern Numidia, but conversion to Islam still is a minoritary choice, and Berber resistance, with incessant raiding by the Zenetes from the south, persists.
British Isles:
East Anglia regains complete freedom from Mercia, whose power has been shaken by the rise of Wessex
Hesperia (*OTL America):
In central Mexico the Toltec kingdom takes shape around the city of Tula