King Wu was the first to declare Beijing the capital city in 1057 BC. Subsequently, the city has gone by the names of Ji, Zhongdu, Dadu, and finally Beijing when the Ming Dynasty Emperor ChengZu chose the name in 1421. Before 1949, Beijing was known as Peking by the Western world. After 1949, the city’s name returned to Beijing, as it is known today. Since the early 1980s when China initiated economic and market reforms under the late Deng Xiaoping, Beijing has become a truly modern, international city. Beijing City is an independently administered municipal district. She is situated in the northeastern part of China at an elevation of 43.5m above sea level. The climate in Beijing is of the continental type, with cold and dry winters and hot summers. January is the coldest month (-4 Celsius), while July the warmest (26 Celsius). Beijing has a whole area of 16808 sq km (about 6500 sq mi), stretching 160 kilometres from east to west and over 180 kilometres north to south. 38% of it is flat land and 62% mountains. She has 16 districts and 2 counties with Dongcheng, Xicheng, Xuanwu, Chongwen, Chaoyang, Haidian, Fengtai and Shijingshan in or close to the Beijing city proper and Fangshan, Mengtougou, Changping, Tongxian, Shunyi, Daxing, Huairou, Miyun, Pinggu and Yianqing in the outer suburbs. Population in Beijing is about 17 million.