Astrakhan Khanate
The Volga Delta was subject to territorial disputes between the Nogai Horde and the Russian-annexed Astrakhan Khanate in the 1550s. Negotiations between Ismael Beg and Ivan IV established the Buzan as the boundary between the two realms but proceeded to push the horde back further out of the fertile delta region. The counter-clockwise extremity of the modern Kazakhstan–Russia border reflects this history, largely following the leftmost corridors of the delta.