How do the Taihang Mountains separate Hebei from Shanxi?

The Taihang Mountains serve as a significant natural boundary between Hebei and Shanxi provinces, effectively separating the North China Plain in the east from the Shanxi plateau in the west.12

Rising steeply from the plain, the range acts as a formidable physical barrier that has historically hindered movement between the two regions. Despite this, the mountains are traversed by several routes, most notably the "eight passes of the Taihang" and narrow valleys known as the "Eight Gorges," which facilitate transportation via highways and railroads. A primary example is the pass at Jingxing, which is currently utilized by a railroad connecting Shijiazhuang in Hebei to Taiyuan in Shanxi. Additionally, the range is drained by tributary streams of the Hai River system, such as the Hutuo and Zhang rivers, which break through the mountains to connect the interior basins to the eastern plains.12