Different waves of immigration led to subgroups among overseas Chinese such as the new and old immigrants in Southeast Asia, North America, Oceania, the Caribbean, South America, South Africa, and Europe. In the 19th century, the age of colonialism was at its height and the great Chinese diaspora began. Many colonies lacked a large pool of laborers. Meanwhile, in the provinces of Fujian and Guangdong in China, there was a surge in emigration as a result of the poverty and ruin caused by the Taiping rebellion. The Qing Empire was forced to allow its subjects to work overseas under colonial powers. Many Hokkien chose to work in Southeast Asia (where they had earlier links starting from the Ming era), as did the Cantonese. The area of Taishan, in Guangdong province was the source for many of the economic migrants. San Francisco and California was an early American destination in the mid 1800s because of the California Gold Rush. Many settled in San Francisco forming one of the earliest Chinatowns. For the countries in North America and Australasia, great numbers of laborers were also needed in the dangerous tasks of gold mining and railway construction. Widespread famine in Guangdong impelled many Cantonese to work in these countries to improve the living conditions of their relatives. Some overseas Chinese were sold to South America during the Punti-Hakka Clan Wars (1855–1867) in the Pearl River Delta in Guangdong. After World War II many people from the New Territories in Hong Kong emigrated to the UK (mainly England) and to the Netherlands to earn a better living.