The highest mouth of the Sichuan-Tibet South Line is Dongda Mountain, 5,130 meters above sea level, located in Zuogong County in Tibet. Unlike the winding Panshan Highway on the Sichuan-Tibet South Line, the road to the mouth of Dongda Mountain is a straight road, which can't see the end at a glance, and has the name of "the longest and most tangled mountain peak on the Sichuan-Tibet South Line".