Pugachev's Rebellion
Pugachev's Rebellion (Peasants' War 1773-75, Cossack Rebellion) of 1773-75 was the principal revolt in a series of popular rebellions that took place in the Russian Empire after Catherine II seized power in 1762. It began as an organized insurrection of Yaik Cossacks headed by Yemelyan Pugachev, a disaffected ex-lieutenant of the Imperial Russian Army, against a background of profound peasant unrest and war with the Ottoman Empire. After initial success, Pugachev assumed leadership of an alternative government in the name of the assassinated Tsar Peter III and proclaimed an end to serfdom. This organized leadership presented a challenge to the imperial administration of Catherine II.
Khan-Tuvan
Khan-Tuvan Dyggvi, according to Omeljan Pritsak, was the name of a Khazar khagan of the mid 830s. He led a rebellion of the Kabars against the Khagan Bek. As this rebellion took place roughly contemporaneously with the conversion of the Khazars to Judaism, Pritsak and others have speculated that the rebellion had a religious aspect.
Omeljan Pritsak speculated that a Khazar khagan named Khan-Tuvan Dyggvi, exiled after losing a civil war, settled with his followers in the Norse-Slavic settlement of Rostov, married into the local Scandinavian nobility, and fathered the dynasty of the Rus' khagans. Zuckerman dismisses Pritsak's theory as untenable speculation, and no record of any Khazar khagan fleeing to find refuge among the Rus' exists in contemporaneous sources. Nevertheless, the possible Khazar connection to early Rus' monarchs is supported by the use of a stylized trident tamga, or seal, by later Rus' rulers such as Sviatoslav I of Kiev; similar tamgas are found in ruins that are definitively Khazar in origin.