The Chuvans of the mid-seventeenth century lived in the remote and mountainous area north of the Anadyr Valley, as reindeer hunters and fishermen or as small-scale reindeer pastoralists. The Russians, who arrived in the 1640s and 1650s, imposed a general annual fur tax ( iasak ) on each able-bodied man between 15 and 50 years of age. Tax registration and annual payments were made at an Anadyr fortress built and equipped by a Russian military garrison. With the beginning of the Chukchee expansion and the Russian-Chukchee hostilities in the 1700s, the Chuvans moved closer to the fortress and to the Anadyr Valley, losing most of their domestic reindeer and becoming gradually mixed with the remnants of other Yukagir bands already subdued by the Russians. Northern groups of Chuvans left in their home area were assimilated by the Chukchee during the eighteenth century. Both their original Chukchee names (Chavan, Chaun) and the Yukagir label "Sholilayi" (the Russian form of "Shelagi") are still found in some modern place-names (e.g., Chuan Bay, Chaun River, and Cape Shelagski on the East Siberian Sea shore). The Anadyr Chuvans were totally destroyed by the Chukchee by the 1770s. After the abandonment of the Anadyr fortress they fled to the Russian settlements along the Kolyma and Penzhina rivers. Some of their descendants returned to the Anadyr Valley between 1820 and 1850, already a creole population mixed with Russians, Tungus, and Koryaks, who spoke Russian, bore Russian family and first names, and were converted to Orthodox Christianity. They settled around the abandoned fortress and along the nearby rivers to create a mixed community with a few Russian families of peasant and Cossack origin. This creole community received new names, "Anadyrtsy" or "Markovtsy" (after their main village of Markovo), under which they were recorded in pre-1917 sources. A small group of Chuvans in the late nineteenth century turned to reindeer pastoralism and came to resemble the reindeer Chukchee and Koryak.