Lorenz or Lorents Lange (Russian: Лоренц (Лаврентий) Ланг; c. 1690 – 1752) was an official in 18th-century Siberia who dealt with Russo-Chinese trade and diplomacy. His reports were a major influence on Russian policy and an important early source of European knowledge of Siberia, Mongolia and China. He is usually said to have been a cornet in the Swedish cavalry who was taken prisoner at the Battle of Poltava in 1709. . At this time Russo-Chinese trade and diplomacy went through the western border to “Manchuria” since Mongolia was not fully under Chinese control.
https://en.wikipedia.org/wiki/Lorenz_Lange