The archaeological gallery roads (棧道) were roads through remote mountain areas of China. They consisted of wooden planks erected on holes cut into the sides of cliffs. They were most notably used in the Qin Mountains linking the Wei River and the Han River valleys. The first gallery roads were built during the Warring States period (476-221 BC) and used by Qin to invade Shu and Ba. They were fully consolidated into a thriving network during the Han Dynasty. Before the 20th century, very primitive versions were used in the western gorges of the Pamir Mountains.