Tianjin simply known as Jin is situated in the northeastern part of North China Great Plain, bordering the Bohai Sea in the east, leaning against the Yuanshan Mountain in the north, with its terrain traversing the Haihe River through north and south. It has become the hub of communications of North China and the gateway of the capital city. Tianjin is a municipality direct under the Central Government, as well as an opening city. It's situated in the eastern part of the North China Plain, covering an area of 11,300 square km. and with a population of six million. It has a semi-humid continental climate in the warm Temperate Zone. With an annual average temperature of 12 degrees centigrade, and rainfall of 590 millimeters, it has 220 frost-free days per year. It's rich in petroleum, natural gas and sea salt along the coastal area.