Sichuan belong to the Kindoms of Ba and Shu. After the first emperor of the Qin Dynasty unified China (221 B.C.), Shu and Ba Prefectures were set up here. In 1001 (during the Song Dynasty) it was divided into four administrative zones — Yizhoulu (for Chendu), Zizhoulu (for Santai), Lizhoulu (for Guangyuan) and Kuizhoulu (for Fengjie). These four Lu were called “four ravine lu” which is the origin of Sichuan (Sichuan in Chinese means “four ravines”). In the year of 1286 during the reign of Kublai Khan, the first emperor of the Yuan Dynasty, it was formally designated as a province.
Sichuan Province has tremendous climatic difference resulting from the physical variation. In the eastern basin it is subtropical monsoon climate characterized by warm winter and hot summer, early spring and rainy autumn. It is wet and foggy and has little sunshine. The western part of province has temperate or subtropical plateau climate, while the southern part of shows marked variation in climates in the mountains and canyons. Frost-free period in the basin is 280-330 days per year, but on the plateau is only less than 90 days. The average annual precipitation of the province is 500-1200 mm, of which the basin has much larger share than the plateau.