[16][2] "[...] Misit etiam cum eis quosdam, qui se, id est gentem suam, Rhos vocari dicebant, quos rex illorum, Chacanus vocabulo, ad se amicitiae, sicut asserebant, causā direxerat, petens per memoratam epistolam, quatenus benignitate imperatoris redeundi facultatem atque auxilium per imperium suum totum habere possent, quoniam itinera per quae ad illum Constantinopolim venerant, inter barbaras et nimiae feritatis gentes immanissimas habuerant, quibus eos, ne forte periculum inciderent, redire noluit.

When questioned by the Frankish king Louis the Pious at Ingelheim, they stated that their leader was known as chacanus (hypothesized to be either the Latin word for "khagan" or a deformation of Scandinavian proper name Håkan),[e] that they lived far to the north, and that they were Swedes (comperit eos gentis esse sueonum).

[28][17] Thirty years later, in spring 871, the eastern and western Roman Emperors, Basil I and Louis II of Italy, quarrelled over control of Bari, which had been besieged by Arabs.

[33] Constantin Zuckerman comments that Ibn Rustah, using the text of the Anonymous Note from the 870s, attempted to accurately convey the titles of all rulers described by its author, which makes his evidence all the more invaluable.

In a legendary story about a siege of the Tsanars in the Caucasus in 854, mention is made of "the overlords (sahib) of the Byzantines (al-Rum), of the Khazars, and of the Slavs (al-Saqaliba)", which Zuckerman connected with a supposed Rus' khagan.

[2][37] According to Zuckerman, Ibn Khordadbeh and other Arab authors often confused the terms Rus and Saqaliba when describing Caspian expeditions of the Rusʹ in the 9th and 10th centuries.

[20] The three later Old East Slavic sources mentioning a kagan (Hilarion of Kiev's 11th-century Sermon on Law and Grace, and the 11th-century Saint Sophia Cathedral, Kyiv inscription) or kogan (the 12th-century The Tale of Igor's Campaign) have generally been understood to refer to the ruler of Kievan Rus'.

[27][2] According to Halperin (1987), the title kagan in the Annales Bertiniani sub anno 839, Hilarion's Sermon, and in The Tale of Igor's Campaign all apply to "the ruler of Kiev".

"[15] Hilarion's Sermon on Law and Grace mentions the word kagan (Old East Slavic: каганъ, romanized: kaganŭ) throughout the text,[38] a total of five times.

[12][39] A colophon preserved in a 15th-century manuscript, at the end of a set of works usually attributed to Hilarion, adds one more mention: Быша же си въ лѣто 6559 (1051), владычествующу благовѣрьному кагану Ярославу, сыну Владимирю.

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.

[73][74] Based on his examination of the archaeological evidence, Zuckerman concludes that Kiev originated as a fortress on the Khazar border with Levedia and that only after the Magyars departed for the west in 889 did the middle Dnieper region start to progress economically.

[76][clarification needed] Recent archaeological research, conducted by Anatoly Kirpichnikov and Dmitry Machinsky, has raised the possibility that this polity was based on a group of settlements along the Volkhov River, including Ladoga, Lyubsha, Duboviki, Alaborg, and Holmgard (modern Rurikovo Gorodische).

[2][77] "Most of these were initially small sites, probably not much more than stations for re-fitting and resupply, providing an opportunity for exchange and the redistribution of items passing along the river and caravan routes".

[78] If the anonymous traveller quoted by ibn Rustah is to be believed, the Rus of the Khaganate period made extensive use of the Volga route to trade with the Near East, possibly through Bulgar and Khazar intermediaries.

[citation needed] His description of the Rus' island suggests that their center was at Holmgard, an early medieval precursor of Novgorod whose name translates from Old Norse as "the river-island castle".

[citation needed] This account prompted Johannes Brøndsted to assert that Holmgard-Novgorod was the khaganate's capital for several decades prior to the appearance of Rurik, including the time of the Byzantine embassy in 839.

[82] In stark contrast, George Vernadsky believed that the khagan had his headquarters in the eastern part of the Crimea or in the Taman Peninsula and that the island described by Ibn Rustah was most likely situated in the estuary of the Kuban River.

[83] Neither of these theories has won many adherents, as archaeologists have uncovered no traces of a Slavic-Norse settlement in the Crimea region in the 9th century and there are no Norse sources documenting "khagans" in Scandinavia.

[55] Vasil’evskii (1915) thought the Rhos were an indigenous people living near the mouth of the Dnieper into the Black Sea, and that the khagan was their Khazar master.

[100] Golden concluded that the Rus' Khaganate was a puppet state set up by the Khazars in the basin of the Oka River to fend off recurring attacks of the Magyars.

[102][clarification needed] This theory is echoed by Thomas Noonan, who asserts that the Rus' leaders were loosely unified under the rule of one of the "sea-kings" in the early 9th century, and that this "High King" adopted the title "khagan" to give him legitimacy in the eyes of his subjects and neighboring states.

[49][2] Zuckerman dismisses Pritsak's theory as untenable speculation,[j] and no record of any Khazar khagan fleeing to find refuge among the Rus' exists in contemporaneous sources.