In the latter half of the 19th century, czarist Russia coerced the Qing government into signing a series of unequal treaties by which it seized vast stretches of Chinese territory. In 1858, by the Treaty of Aigun, China ceded to Russia more than 600,000 square kilometres of territory north of the Heilong [Amur] River, which forms the northern border of present-day Heilongjiang Province. It also designated some 400,000 square kilometres of territory east of the Wusuli River, which now forms the eastern border of the province, as an area of "common jurisdiction". In 1860, through the Additional Treaty of Beijing, this area was incorporated into Russia's territory. The Additional Treaty also determined the basic position of the western boundary between the two countries. In 1864, on the basis of this boundary, Russia compelled the Qing government to sign the Protocol of Chuguchak, ceding more than 440,000 square kilometres of territory northwest of present-day Xinjiang Autonomous Region. From 1881 to 1884, by the Treaty of St. Petersburg and five additional agreements, Russia acquired 70,000 more square kilometres in the West of China. Altogether, Russia seized over 1.5 million square kilometres of Chinese territory.