Meanwhile, north of the Manchu homeland, adventurers Vassili Poyarkov (1643–1646) and Yerofei Khabarov (1649–1653) had started to explore the Amur River valley for Tzarist Russia. In 1653 Khabarov was recalled to Moscow and replaced by Onufriy Stepanov, who assumed command of Khabarov's Cossack troops. Stepanov went south into the Sungari River, along which he exacted "yasak" (fur tribute) from native populations such as the Daur and the Duchers, but these groups resisted because they were already paying tribute to the Shunzhi Emperor ("Shamshakan" in Russian sources). In 1654 Stepanov defeated a small Manchu force that had been despatched from Ningguta to investigate Russian advances. In 1655 another Qing commander, the Mongol Minggadari (d. 1669), defeated Stepanov's forces at fort Kumarsk on the Amur, but this was not enough to chase the Russians. In 1658, however, Manchu general Šarhūda (1599–1659) attacked Stepanov with a fleet of 40 or more ships that managed to kill or capture most Russians. This Qing victory temporarily cleared the Amur valley of Cossack bands, but Sino-Russian border conflicts would continue until 1689, when the signature of the Treaty of Nerchinsk fixed the borders between Russia and the Qing.