Shudao

The ancient roads from Qin (Shaanxi) to Shu (Sichuan);
= city, = county (县, *xiàn*), thin lines = ill documented

The Shudao (Chinese: 蜀道; pinyin: Shǔdào), or the Road(s) to Shu, is a system of mountain roads linking the Chinese province of Shaanxi with Sichuan (Shu), built and maintained since the 4th century BC. Technical highlights were the gallery roads, consisting of wooden planks erected on wooden or stone beams slotted into holes cut into the sides of cliffs.