Xiamen, historically romanized as Amoy, is a sub-provincial city in southeastern Fujian, People's Republic of China, beside the Taiwan Strait. It is divided into six districts: Huli, Siming, Jimei, Tong'an, Haicang, and Xiang'an. All together, these cover an area of 1,700.61 square kilometers with a population of 5,163,970 as of 2020 and estimated at 5.308 million as of 31 December 2022. The urbanized area of the city has spread from its original island to include most parts of all six of its districts, as well as 4 Zhangzhou districts, which form a built-up area of 7,284,148 inhabitants. This area also connects with Quanzhou in the north, making up a metropolis of nearly ten million people. The Kinmen Islands administered by the Republic of China lie less than 6 kilometers away separated by Xiamen Bay. 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.