The Sichuan Basin (Chinese: 四川盆地; pinyin: Sìchuān Péndì), or Szechwan Basin, is a lowland region in southwestern China. Despite its historical name, it is not only synonymous to Sichuan province, comprising its central and eastern portions as well as part of Chongqing Municipality (which itself was, until 1997, politically part of Sichuan). Due to its relative flatness and fertile grounds, it is heavily populated with a population of more than 100 million. In addition to being a dominant geographical feature of the region, the Sichuan basin also constitutes a cultural sphere that is distinguished by its own unique customs, cuisine, and dialects. It is also called the "Red Basin." It is famous for rice cultivation. It is also the principal gas-producing region of China.
Mountain ranges 
Mountains frame the Sichuan Basin on all sides:
Hills, plains and rivers 
The Sichuan Basin consists of low hills and alluvial plains, and several major rivers flow into the Chang Jiang (Yangtze River), which passes through the southern part of the basin. The seismically active Longmenshan Fault - the source of the catastrophic 2008 Sichuan earthquake - runs along the western boundary of the basin, separating it from the Tibetan plateau to the west.
A moist, often overcast, four-season climate dominates here, with cool to mild winters, with occasional frost, and hot, very humid summers; the intensity of summer varies rather widely, depending on location. See the articles on Chongqing and Chengdu for further details.
These days the Sichuan Basin flatlands are mostly covered by farmers' fields and cities, while the original Sichuan Basin evergreen broadleaf forests landscapes have been reduced to small patches on occasional steep hill slopes, on a few sacred mountains such as Mount Emei, or around temples. A greater variety of natural landscapes and wildlife has been at least partially preserved in the mountains surrounding the basin. The natural ecosystems of these mountains have been classified by the World Wildlife Fund as the Qionglai-Minshan conifer forests and the Daba Mountains evergreen forests. It was in the hilly Lichuan County, on the eastern mountain fringe of the basin, where the Dawn Redwood (Metasequoia glyptostroboides, previously only known in fossils and thought to be extinct) was discovered in 1944. The Dawn Redwood is distinctive because it is a deciduous conifer.
- Energy Citations Database (ECD) - - Document #7024946
- "Sichuan Basin evergreen broadleaf forests". Terrestrial Ecoregions. World Wildlife Fund.
- "Qionglai-Minshan conifer forests". Terrestrial Ecoregions. World Wildlife Fund.
- "Daba Mountains evergreen forests". Terrestrial Ecoregions. World Wildlife Fund.