Hokkien originated from Quanzhou. After the Opium War in 1842, Xiamen (Amoy) became one of the major treaty ports to be opened for trade with the outside world. From mid-19th century onwards, Xiamen slowly developed to become the political and economical center of the Hokkien-speaking region in China. This caused Amoy dialect to gradually replace the position of dialect variants from Quanzhou and Zhangzhou. From mid-19th century until the end of World War II, western diplomats usually learned Amoy Hokkien as the preferred dialect if they were to communicate with the Hokkien-speaking populace in China or South-East Asia. In the 1940s and 1950s, Taiwan also held Amoy Hokkien as its standard and tended to incline itself towards Amoy dialect.