Aldan River
Moskvitin is first attested in 1626 as residing among the Cossacks in Tomsk. In 1636 or 1637 Dmitry Kopylov with 54 men including Moskvitin were sent east toward Yakutsk. He went down the Lena River and up the Aldan River and on 28 June 1638 founded the fort of Butalsk about 100 km above the mouth of the Maya River and about 250 km southeast of Yakutsk. From a local Shaman Kopylov learned of a south-flowing "River Shirkol" (Zeya River?) where sedentary people grew grain and had cattle and, according to some sources, a silver deposit. In May 1639 he sent Moskvitin with 20 Tomsk Cossacks and 19 Krasnoyarsk Cossacks and an Evenk guide eastward. They went down the Aldan River and up the Maya River and from the upper Maya crossed the Dzhugdzhur Mountains and went down the Ulya River and in August 1639 reached the Sea of Okhotsk.