Jiangxi is centered on the Gan River valley, which historically provided the main north-south transport route of south China. The corridor along the Gan River is one of the few easily traveled routes through the otherwise mountainous and rugged terrain of the south-eastern mountains. This open corridor was the primary route for trade and communication between the North China Plain and the Yangtze River valley in the north and the territory of modern Guangdong province in the south. As a result Jiangxi has been strategically important throughout much of China's history. Major cities are, Nanchang, Jiujiang, Ganzhou, Xinyu, Pingxiang, Jingdezhen, Ji'an, Yingtan and Fuzhou.