Tianjin is a metropolis in northern coastal China and one of the five national central cities of China, with a total municipal population of 15,469,500. It is governed as one of the four direct-controlled municipalities of the PRC and is thus under direct administration of the central government. Tianjin borders Hebei Province and Beijing Municipality, bounded to the east by the Bohai Gulf portion of the Yellow Sea. Part of the Bohai Economic Rim, it is the largest coastal city in northern China.