Why is the Jialing River valley an important route between Shaanxi and Sichuan?

The Jialing River valley serves as a vital communications artery between the Wei River basin in central Shaanxi and the cities of the Sichuan Basin because it provides the only major break in the formidable Daba Mountains chain.31

While the mountainous southern region of Shaanxi is generally difficult to traverse due to the Qin Mountains and the Daba range, the Jialing River cuts through the Daba chain in the far southwest of the province. This natural passage allows for a route that connects the Wei River valley to Sichuan and the southwest. Historically and in the modern era, this valley has been a primary corridor for transportation, with roads and railroads—such as the line connecting Baoji to Chengdu—roughly paralleling the river's course to overcome the region's rugged terrain.123