Oirat (Torghut and Dörbet) khanate on the lower Volga founded after Kho Orluk led the Torghuts west from Dzungaria c. 1630; peaked under Ayuka Khan, supplied tributary cavalry to Russia, and largely dissolved when Ubashi Khan led the 1771 exodus back toward Dzungaria.
Autonomy eroded by the Russian state after Ayuka Khan's death (1724); most of the khanate migrated east in the 1771 Torghut flight, and Catherine II abolished the khanate that same year.
The definitive English scholarly monograph on the Kalmyk Khanate from the Volga arrival to the 1771 exodus.