favorite, took advantage of the emperor's indulgence to become one of the most corrupt officials in the history of the dynasty. Qianlong's son, the Jiaqing Emperor (r. 1796–1820), eventually forced Heshen to commit suicide. Population was stagnant for the first half of the 17th century due to civil wars and epidemics, but prosperity and internal stability gradually reversed this trend. The Qianlong Emperor bemoaned the situation by remarking, "The population continues to grow, but the land does not." The introduction of new crops from the Americas such as the potato and peanut allowed an improved food supply as well, so that the total population of China during the 18th century ballooned from 100 million to 300 million people. Soon farmers were forced to work ever-smaller holdings more intensely. The only remaining part of the empire that had arable farmland was Manchuria, where the provinces of Jilin and Heilongjiang had been walled off as a Manchu homeland. Despite prohibitions, by the 18th century Han Chinese streamed into Manchuria, both illegally and legally, over the Great Wall and Willow Palisade. In 1796, open rebellion broke out among followers of the White Lotus Society, who blamed Qing officials, saying "the officials have forced the people to rebel." Officials in other parts of the country were also blamed for corruption, failing to keep the famine relief granaries full, poor maintenance of roads and waterworks, and bureaucratic factionalism. There soon followed uprisings of "new sect" Muslims against local Muslim officials, and Miao tribesmen in southwest China. The White Lotus Rebellion continued for eight years, until 1804, when badly run, corrupt, and brutal campaigns finally ended it. Rebellion, unrest, and external pressure At the start of the dynasty, the Chinese empire continued to be the hegemonic power in East Asia. Although there was no formal ministry of foreign relations, the Lifan Yuan was responsible for relations with the Mongol and Tibetans in Central Asia, while the tributary system, a loose set of institutions and customs taken over from the Ming, in theory governed relations with East and Southeast Asian countries. The Treaty of Nerchinsk (1689) stabilized relations with Tsarist Russia. However, during the 18th century European empires gradually expanded across the world, as European states developed economies built on maritime trade, colonial extraction, and advances in technology. The dynasty was confronted with newly developing concepts of the international system and state-to-state relations. European trading posts expanded