Traditional trade routes that penetrate the natural barrier of the Himalayas are critical for connecting major Chinese and South Asian markets. Research on these trade routes can contribute significantly to facilitating the construction of the South Asian Corridor and enhancing trans-Himalayan connectivity. Combining historical literature, field surveys, and geographic information system (GIS) techniques, this study examined the spatial distribution characteristics and evolution process of the routes, focusing on transverse valleys of the Himalayan arc. The key findings were as follows. First, there are 21 traditional trade routes traversing the Himalayan region: six Sino-Nepalese routes, four Sino-Bhutanese routes, and eleven Sino-Indian routes. Second, the evolution of traditional trade routes has entailed five distinct phases: an incipient period (pre-7th century), formation (7th century-842 AD), development (842-1959), decline (1959-1962) and recovery (1962-present). Third, the incipient and formative developmental phases were prompted by the spread of Buddhism and the exchange of goods. The stability of local governments in Tibet and Central China and favourable border trade policies along with Britain's colonial expansion and commercial interests stimulated further development of traditional trade routes. However, India's strategic miscalculation and "Forward Policy" instigated the decline phase, while the demands of regional cooperation and development are currently the key drivers of the restoration and construction phase. Finally, to shelve disputes, promote cooperation and development, and enhance political mutual trust, governments should recover and construct traditional trade routes by replanning and constructing border trade markets, expanding border trade, developing pilgrimage and tourism, and strengthening cross-border cooperative research under global climate change.