It was against this volatile background that the Tsar's officials worked to transform yasak from an exchange of items (the centuries-old concept inherited from the Khanate of Siberia and Golden Horde) into a fixed and regular levy, but the process took centuries to complete. In many frontier areas it turned out that "the regular supply of... presents to the local ruler and his nobles was, in fact, the only way to secure the natives' cooperation". In the basin of the Volga, yasak was replaced with a regular tax in the 1720s, and most of Siberia followed suit in 1822. A largely symbolic form of yasak continued to be levied from the nomadic peoples of Eastern Siberia (Yakuts, Evenks, Chukchi) until the Russian Revolution of 1917.