Xiamen Island possessed a natural harbor in Yundang Bay, but Fujian's international trade was long restricted to Quanzhou or to Guangzhou in Guangdong. Under the Qing, both before and after the First Opium War, there was a large-scale emigration of Chinese from southern Fujian who spread Hokkien-speaking communities to Singapore, Malaysia, Indonesia and the Philippines. The overseas Chinese continue to support Xiamen's educational and cultural institutions. As part of the Opening Up Policy under Deng Xiaoping, Xiamen became one of China's original four special economic zones opened to foreign investment and trade in the early 1980s. Its former harbor was enclosed using land excavated during the city's expansion, however, the city remains an island connected by bridges to the rest of mainland China.