Between 1654 and 1675, the tsar dispatched a series of ambassadors to the Qing emperors. Each, in turn, failed to follow proper protocol. They failed to either kowtow—a specific act of supplication in which the individual kneels three times and touches one's head to the floor nine times—or otherwise display sufficient respect to the emperor. After a Cossack brought back a letter from Emperor Kangxi, in 1675 the tsar decided to send another ambassador, the Moldavian Nikolai Garilovich Spafarii (in Romanian, Nicholaie Spatarul Milescu, ca. 1636–1708), to China. The emperor gave him gifts for the tsar, but when he refused to receive the gifts on his knees, the gifts were withdrawn and he was asked to leave Beijing. The Chinese Bureau of Foreign Affairs set conditions for future communications between China and Russia, and told Spafarii-Milescu that the Russians should not disturb the peace in Siberia—something they failed to do until the negotiation of the Treaty of Nerchinsk (1689), which better defined the border between China and the tsardom.