empires' areas of control met in what is today eastern Kazakhstan and Western Xinjiang. The 1851 Treaty of Kulja legalized trade between both countries in the region. Russian encroachment In 1858, during the Second Opium War, China grew increasingly weaker as the "Sick man of Asia" while Russia strengthened and eventually annexed the north bank of the Amur River and the coast down to the Korean border in the "Unequal Treaties" of Treaty of Aigun (1858) and the Convention of Peking (1860). Russia and Japan gained control of Sakhalin Island. The Manza War (1868) was the first attempt by Russia to expel the Chinese from the territory that it controlled. Hostilities broke out around Peter the Great Gulf, Vladivostok, when the Russians tried to shut off gold mining operations and to expel Chinese workers there. The Chinese resisted a Russian attempt to take Askold Island and in response, two Russian military stations and three Russian towns were attacked by the Chinese, and the Russians failed to oust the Chinese. Russia's special status Unlike other Western countries, who deal with the Qing court on a monarch to monarch basis, Sino–Russian relations were governed by administrative bodies, the Qing's Board of Foreign Affairs (Lifan Yuan) and the Russian Senate (Senat). Unlike the Netherlands and Portugal in the 18th century, who were considered part of the tribute system, Russia was able to trade directly with Beijing, and their relations were under the jurisdiction of Mongolian and Manchu border officials. Russia established an Orthodox mission in Beijing in the early 18th century, and was able to escape the anti Christian persecutions of the Qing dynasty. The Great Game and the 1870s Xinjiang border Dispute A British observer, Demetrius Charles de Kavanagh Boulger, suggested a British-Chinese alliance to check Russian expansion in Central Asia. During the Ili crisis, when Qing China threatened to go to war against Russia over the Russian occupation of Ili, a British officer, Charles George Gordon, was sent to China by Britain to advise China on its military options against Russia in a potential war between China and Russia. The Russians occupied the city of Kuldja, in Xinjiang, during the Dungan revolt (1862–1877). After General Zuo Zongtang and his Xiang Army crushed the rebels, they demanded for Russia to return the occupied regions. General Zuo Zongtang was outspoken in calling for war against Russia and hoped to settle the matter by