Fur trade marten furs could generate in international markets spurred a "fur fever" in which many Russians moved to Siberia as independent trappers. From 1585 to 1680, tens of thousands of sable and other valuable pelts were obtained in Siberia each year. The primary way for the Muscovite state to obtain furs was by exacting a fur tribute from the Siberian natives, called a "yasak". "Yasak" was usually a fixed number of sable pelts which every male tribe member who was at least fifteen years old had to supply to Russian officials. Officials enforced "yasak" through coercion and by taking hostages, usually
California Fur Rush California Fur Rush Before the 1849 California Gold Rush, American, English and Russian fur hunters were drawn to Spanish (and then Mexican) California in a California Fur Rush, to exploit its enormous fur resources. Before 1825, these Europeans were drawn to the northern and central California coast to harvest prodigious quantities of southern sea otter ("Enhydra lutris nereis") and fur seals ("Callorhinus ursinus"), and then to the San Francisco Bay Area and Sacramento – San Joaquin River Delta to harvest beaver ("Castor canadensis"), river otter ("Lontra canadensis"), marten, fisher, mink, gray fox ("Urocyon cinereoargenteus"), weasel, and harbor seal. It was