The Byzantine Emperor Constantine VII is the principal source of the Kabars' history. He dedicated a whole chapter—chapter 39—to the Kabars (or Kabaroi) in his De Administrando Imperio, which was completed around 950. The Emperor described the Kabars as "a race of Khazars" who had risen up against the Khagan. The uprising was crushed, and some of them were massacred, but others escaped and joined the Magyars in the Pontic steppes.
The Kabars rebelled against the Khazar Khaganate in the early ninth century; the rebellion was notable enough to be described in Constantine Porphyrogenitus's work De Administrando Imperio. Subsequently the Kabars were expelled from Levedia in the Khazar Khaganate leading the Magyar tribal confederacy called Hét-Magyar (meaning "seven Hungarians") to Etelköz while others under Khan-Tuvan sought refuge by joining the Rus' people. One of the names on the Kievian Letter is "Kiabar", showing that some Kabars settled in Kiev with the Rus' as well. According to Magocsi, "A violent civil war took place during the 820s [...] The losers of the internal political struggle, known as Kabars, fled northward to the Varangian Rus' in the upper Volga region, near Rostov, and southward to the Magyars, who formerly had been loyal vassals of the Khazars. The presence of Kabar political refugees from Khazaria among the Varangian traders in Rostov helped to raise the latter's prestige, with the consequence that by the 830s a new power center known as the Rus' Kaganate had come into existence."
In 894, the Byzantine emperor Leo VI, then at war with Simeon, the Bulgarian czar (893–927), called the Hungarians to his aid. The Magyars, led by Árpád, crossed the Danube and attacked Bulgaria. The Bulgarians, in turn, appealed to the Pechenegs, now masters of the steppe, who attacked the Hungarians in the rear. Toward 850 or 860, driven from Levedia by the Pechenegs, they entered Atelkuzu (Etelköz) taking refuge in the mountains of Transylvania. At that moment, Arnulf, duke of Carinthia, at war with the Slav ruler Svatopluk, prince of Great Moravia (885–894), decided like the Byzantines to appeal to the Hungarians. The Hungarians overcame Svatopluk, who disappeared in the conflict (895). The Magyars reached the Danube river basin around 880. As the vanguard and rearguard, the Kabars, or Cowari as they were known in Latin, assisted in the Magyar invasion of Pannonia and the subsequent formation of the Principality of Hungary in the late 9th century. Great Moravia collapsed, and the Hungarians took up permanent abode in Hungary (907).
The presence of a Turkic aristocracy among the Hungarians could explain the Byzantine protocol by which, in the exchange of ambassadors under Constantine Porphyrogenitus, Hungarian rulers were always referred to as "Princes of the Turks".
Archaeological theories on Religion
At least some Kabars were of the Khalyzians' Jewish faith; others may have been Christians, Muslims or shamanists. Bunardžić dated Avar-Bulgar graves excavated in Čelarevo, containing skulls with Mongolian features and Judaic symbols, to the late 8th and 9th centuries. Erdely and Vilkhnovich consider the graves to belong to the Kabars who eventually broke ties with the Khazar Empire between the 830s and 862.
The Kabars supposedly left scattered remains and some cultural and linguistic imprints, but this is debatable.
The Mihai Viteazu inscription (Alsószentmihály inscription), discovered in the 20th century in present-day Romania, is one of few surviving relics of the Kabars. It was transcribed by the archaeologist-historian Gábor Vékony. According to the transcription, the meaning of the two-row inscription is the following: (first row) "His mansion is famous." and (second row) "Jüedi Kür Karaite." or "Jüedi Kür the Karaite.".
- Róna-Tas, András (1996): A honfoglaló magyar nép. Bevezetés a korai magyar történelem ismeretébe [The conquering Hungarian nation. Introduction to the knowledge of the early Hungarian history]. Budapest: Balassi Kiadó, ISBN 963-506-106-4
- Khavars in the Rovaspedia
- The Qavars (Qabars) and their Role in the Hungarian Tribal Federation by Sándor László Tóth
- According to the Turcologist András Róna-Tas, the name Kabar" is faulty, the right pronunciation is Khavar. Róna-Tas, András (1996a): A honfoglaló magyar nép. Bevezetés a korai magyar történelem ismeretébe [The conquering Hungarian nation. Introduction to the knowledge of the early Hungarian history]. Budapest: Balassi Kiadó, p. 273
- Golden 1980, pp. 134-135.
- Kristó 1996, p. 149.
- Pritsak, Origins of Rus' 1:28, 171, 182.
- ""A violent civil war took place during the 820s [...] The losers of the internal political struggle, known as Kabars, fled northward to the Varangian Rus' in the upper Volga region, near Rostov, and southward to the Magyars, who formerly had been loyal vassals of the Khazars. The presence of Kabar political refugees from Khazaria among the Varangian traders in Rostov helped to raise the latter's prestige, with the consequence that by the 830s a new power center known as the Rus' Kaganate had come into existence."Magocsi, Paul Robert (2010). A History of Ukraine: A Land and Its Peoples. Toronto: University of Toronto Press. p. 62.
- Peter F. Sugar, Péter Hanák, Tibor Frank, A History of Hungary, Indiana University Press, 1994 page 11.
- René Grousset, The Empire of the Steppes, p.178. Rutgers University Press, 1988. ISBN 0-8135-1304-9
- Golden, Peter B. "The Conversion of the Khazars to Judaism." The World of the Khazars: New Perspectives. Brill, 2007. p. 150.
- Vékony, Gábor (2004): A székely rovásírás emlékei, kapcsolatai, története [The Relics, Relations and the History of the Szekely Rovas Script]. Publisher: Nap Kiadó, Budapest. ISBN 963-9402-45-1
- Vékony, Gábor (1997): Szkíthiától Hungáriáig: válogatott tanulmányok. [From Scythia to Hungary: selected Studies] Szombathely: Életünk Szerk. Magyar Írók Szövetsége. Nyugat-magyarországi Csoport. Ser.: Életünk könyvek, p. 110