Treaty of Aigun
In the mid 19th century, the second Russian expansion took place after Russia lost the Crimean War (1853–1856). A number of Cossack settlements were established on the Amur river. China had become far weaker than Russia at the time and ceded territory to Russia in the Treaty of Aigun of 1858 and by the Convention of Peking of 1860 (see Amur Annexation).