Grasslands cover most of the west of Jilin; the Changbai Mountains define the eastern border. Timber is a major natural resource and the oil has a production capacity of 5m tons a year. Jilin is an important grain-growing region. The 1997 corn crop of 12,6m tons was the nation's biggest. The Japanese occupation left a legacy of a good rail network, five times as much as Guangdong province. Jilin has the China's highest production of trucks and is second in the production of autos.