According to the field of genetic genealogy, people first resided in Siberia by 45,000 BCE and spread out east and west to populate Europe and the Americas, including the prehistoric Jomon people of Japan, who are the ancestors of the modern Ainu. According to Vasily Radlov, among the earliest inhabitants of Central Siberia were the Yeniseians, who spoke a language different from the later Uralic and Turkic people. The Kets are considered the last remainder of this early migration. Migrants are estimated to have crossed the Bering Land Bridge into North America more than 20,000 years ago.