Yunnan's major rivers flow through the deep valleys between the mountains. The plateau region has moderate temperatures. The western canyon region is hot and humid at the valley bottoms, but there are freezing winds at the mountaintops. Rice is the major crop. There are enormous timber reserves in the canyon region.
Mining is the leading industry as Yunnan has one of the world's largest tin deposits.
Other industries produce paper, sugar, leather, and rugs. Highways are well developed, and trucks reach remote villages. Railroads are growing continually. Yunnan has been a province since 1253. It was governed by local leaders until the 20th century, when it was brought under central government control.