This route consists of two sections: the first section is from Srinagar to Lhasa, and the second section is from Lhasa to Kangding (Figure 3, No.1). Almost all routes from the west to the east are connected to this route. Thus, this route was the most important traditional trade route in the Himalayan region. There was a large population and many settlements along the route, such as Srinagar in Kashmir, Leh in Ladakh, Gartok (Garyarsa, the centre of western Tibet), Shigatse, Lhasa, Qamdo, and Kangding. The section from Srinagar to Lhasa was regarded as “The Musk Road”, “The Wool Road”, and “The Salt Road” because musk, wool, and salt were the most representative commodities in these regions (Fang, 2015). According to the study of Fang (2015), there were 16 post stations from Srinagar to Leh, 18 post stations between Leh and Gartok, and 22 post stations from Gartok along the Yarlung Zangbo valley to Lhasa. Additionally, the traders could travel from Srinagar to India, Afghanistan, and other South and Central Asian regions. They could also travel from Leh through the Karakoram pass to the Tarim Basin in Xinjiang, China (Tong, 2017). The section from Kangding to Lhasa was the main Sino-Tibetan trade route and was of great significance to the stability and development of Tibet.

Western trade routes, which primarily connected northwest India and western Tibet, were mainly used for pilgrimage and commerce by Hindus, Buddhists, farmers and herders, and others (Lv, 2017). Additionally, early Europeans entered Tibet for expedition mainly through these routes.

There were mainly five trade routes in the western Himalayas: Sumsan Sumba route, from Kyelang in Rahul and Spiti to Chulu Songjie and Tashigong in Tibet along the Spiti River (Figure 3, No.2); Shipki route, from Shimla, along Sutlej River, through Shipki La pass to Zanda and Gartok in Tibet (Figure 3, No.3); Gonggong Sumba route, from Dehradun to Toling, Gartok, and other places in Tibet along Bhagirathi River (Figure 3, No.4); Mana and Niti route, from Srinagar in Pauri Garhwal district, along Ganges River, through Mana pass or Niti pass to Zanda and other places in Tibet (Figure 3, No.5). In 1624, Andrade, a Jesuit missionary, and his fellows, taking the missionary opportunity, arrived at Guge in Tibet along the Sutlej valley through Mana pass to explore land routes from Europe to China, but the action eventually led to the war between Ladakh and Guge, resulting in the destruction of Guge (Wu, 1992). Lipu Lekh route, from Moradabad, along the Kali River, through Lipu Lekh pass to Burang, Gyanyima, Mount Kailash, and other places in Tibet (Figure 3, No.6).

The traditional trade between China and Nepal has a long history. Since the Han and Tang dynasties, there have been silk trade routes from the Chinese mainland through Tibet, Nepal and India. There were six trade routes between China and Nepal: Majia Zangbo route, from Nepal to Burang and Mount Kailash along Karnali River (Figure 3, No.7); Mustang route, from Mustang to Zhongba in Tibet along Kali Gandaki River (Figure 3, No.8); Gyirong route, from Katmandu to Gyirong, and other places in Tibet along Gyirong valley (Figure 3, No.9); Zhangmu route, from Katmandu to Nyalam, and other places in Tibet along Zhangmu valley (Figure 3, No.10); Rongxia route, from Nepal to Rongxia, Tingri, and other places in Tibet along Rongxia valley (Figure 3, No.11); Chentang route, from Nepal to Tingkye, and other places in Tibet along Chentang valley or Gama valley (Figure 3, No.12).

Among these routes, the Gyirong route and Zhangmu route were the most commonly used and the most prosperous. The Gyrong route is also known as the “Ancient Tubo-Nepal Road”, by which Bhrikuti of Nepal married Tubo from Nepal, and Tang Dynasty diplomats Li Yibiao and Wang Xuance arrived in India (Duojie, 1995).

This route was forced open by British colonists in 1904 and then became the most important trade route between Tibet and South Asia during the first half of the 20th century (Figure 3, No.13). The British colonists forced the signing of the “Lhasa Convention”, which opened trading ports in Yadong, Gyantse, and Gartok. Since then, this route has developed rapidly, with the British building 11 post stations from Yadong to Gyantse. Before the 1962 war, traffic across this route accounted for 80% of the total border trade volume between India and Tibet, China (Karackattu, 2013).

Under the impacts of a special geographical environment and religious beliefs, the trade between Bhutan and Tibet has been ongoing for a long time, and several traditional trade routes have been formed along the fault valleys of the Himalayas (Williams, 2017; Zha and Ao, 2017), four of which are the main routes. Tremo La route, from Paro in Bhutan to Pagri in Tibet crossing Tremo La pass (Figure 3, No.14). In the 18th century, the British East India Company sent George Bogle to Tibet through this route in an attempt to open the trade route with Tibet (Sarkar and Ray, 2006). Sankosh route, from Punakha in Bhutan to Kangmar in Tibet along Sankosh River (Figure 3, No.15); Lhozhag route, from Tongsa in Bhutan to Lhakhang in Tibet, Shangnan, and Lhasa along Lhobrak River (Figure 3, No.16); Lebo route, from Tashigang in Bhutan to Tsona in Tibet along Manas River (Figure 3, No.17).

Southern Tibet, mainly inhabited by Chinese ethnic groups such as the Lopa, Menpa and Mishmi, was divided into the Loyu, Menyu, and Tsayul regions. Since ancient times, they have continued to trade with Tibetans and people from the Assam plains and have developed trade markets along border regions (Xu, 1936; Zha and Liu, 2014). There were mainly four routes: Tawang route, from Udalguri to Tawang, Tsona crossing Dirang and Se La pass (Figure 3, No.18); Subansiri route, from Assam plains to Thaksin and Lhuntse along Subansiri River (Figure 3, No.19); Motuo route, from Pasighat to Medog, Bome and other places in Tibet along Yarlung Zangbo River (Figure 3, No.20); Zayu route, from Sadiya to Zayu along Zayu River (Figure 3, No.21).

In recent years, new archaeological discoveries and historical records have demonstrated that 5000 years ago (Upper Palaeolithic and Neolithic age), the Tibetan Plateau was closely connected with the surrounding areas of the Himalayas, South Asia, the Central Plains of China, and the upper reaches of the Yellow River (Huo, 2013; Liu, 2017; Xu, 2018). To the early metal-smelting age, small tribes stood in great numbers, and the trade between the tribes was carried out with the war. After a series of merges, the three powerful tribal alliances of Zhang Zhung (Chinese: Xiangxiong), Yarlung tribe, and Sumpa tribe had been gradually formed on the Tibetan Plateau (Zhang, 2016). Because of its superior geographical location, Zhang Zhung, which is centred on the western region of the Tibetan Plateau, has become a regional political, cultural and commercial centre closely related to the Xinjiang, Central Asia and South Asian subcontinents in the Han to Jin dynasties, preliminarily passing through the “Plateau Silk Road” from western Tibet to the Western Regions, Central Asia and the South Asian subcontinent (Huo and Huo, 2017). This road was connected mainly through Ladakh of the Himalayan region (Tong, 2017). After the 6th century AD, the Yalong tribe conquered Zhang Zhung and other tribes, established the Tubo Kingdom, and completed the unification of the Tibetan Plateau, laying the foundation for the formation and development of traditional trade routes.

The Tubo Kingdom reached its peak in the 7th century to 842 AD. First, Tubo opened the “Ancient Tang-Tibet Road” and “Ancient Tubo-Nepal Road”, which were the branches of the Silk Road from Tubo to South Asia, by establishing its capital in Lhasa and allying itself with Zhang Zhung, Muya, Nepal, and Tang Dynasty through political marriage (Duojie, 2016). Second, with its resource advantage, the routes known as “The Musk Route” or “The Salt Route” were opened from Lhasa through Ngari Prefecture and Ladakh to Central Asia and South Asia (Li, 2017). Third, with Buddhism flourishing, Tibetan Buddhism began to spread rapidly to the southern foothills of the Himalayas, such as Bhutan, Sikkim and Ladakh, and gradually opened up trade and pilgrimage routes with these areas.

In 842 AD, Langdama was assassinated by a Buddhist hermit for persecuting Buddhists. From then on, Tubo entered a period of fragmentation, and western Tibet was further divided into three local regimes, Guge, Ladakh and Purang (Huang, 2012). For this reason, a large number of Buddhists fled to the surrounding areas, such as Ngari, Nepal, Bhutan, and Sikkim (Petech and Zhang, 2012), and the trade routes declined to some extent. At the end of the 13th century, the Yuan Dynasty incorporated Tibet into its territory. Yuan put an end to the separatist rule over Tibet and set up post stations along routes, which promoted the construction and development of the routes. The Ming Dynasty followed the Yuan Dynasty’s rule over Tibet and established suzerain-vassal relations with neighbouring areas such as Sikkim and Bhutan, gradually forming a “tributary trade” system. From the end of the 16th century to the middle of the 17th century, European missionaries entered Tibet from Ngari with the banner of missionaries. Their main purpose was to find a land route from Europe to China in the hope of exporting goods to China, but they were unsuccessful (Wu, 1992). In the 18th century, Britain intervened in the South Asian subcontinent and began to seek land access to the Chinese mainland from all directions in the Himalayas. First, Britain defeated Nepal, annexed the Garhwal and Kumaon districts in the western section of the Himalayas, and controlled the traditional trade routes in the western section between India and China (Bergmann, 2016b; Lamb and Deng, 2016a). Then, Britain invaded the Darjeeling of the Sikkim, Bhutan, and Assam plains and controlled the Sino-Bhutanese trade routes. Finally, British colonialists invaded Tibet by force in 1904, opened the trade route from Kalimpong through Yadong to Lhasa, and opened the three trading ports of Yadong, Gyantse, and Gartok (Lamb and Deng, 2016b). In 1914, Britain illegally delineated the McMahon Line and attempted to control and open the Tawang route, Medog route, and Zayu route in southern Tibet (Wu, 1988; Goldstein, 2005; Liang, 2015). After the founding of the People’s Republic of China, the Sichuan-Tibet Highway was constructed in 1954, which further strengthened the connection between Tibet and the hinterland. Subsequently, the agreement between the Republic of India and the People’s Republic of China on Trade and Intercourse between Tibet of China and India was inked on April 29, 1954. According to the agreement, Gartok, Pulanchung (Taklakot), Gyanima-Khargo, Gyanima-Chakra, Ramura, Dongbra, Pulang-Sumdo, Nabra, Shangtse and Tashigong were opened as markets for trade; Shipki La pass, Mana pass, Niti pass, Kungri Bingri pass, Darma pass and Lipu Lekh pass were opened as routes for traders and pilgrims. Meanwhile, the agreement (September 20, 1956) was inked to promote border trade between China and Nepal. Since then, the Sino-Nepalese trade routes have developed rapidly.

After independence (1947), India tried to inherit the legacy of British colonization, including monopolizing trade by controlling traditional trade routes and creating a buffer zone by implementing the “Forward Policy” (Maxwell, 1981). In March 1959, India took advantage of a rebellion in Lhasa of Tibet to interfere in China’s internal affairs. In April of that year, India began to impose an embargo on Tibet and blocked the trade route from Kalimpong to Lhasa, preventing Tibetan merchants and trade caravans from carrying goods through the route and disrupting the normal activities of Chinese commercial agencies in Kalimpong and Kolkata (Dai, 2013a; Dai, 2013b). In mid-1959, India provoked border disputes, including the Longjiu incident in August and the Kongka La incident in October, which led directly to a sharp deterioration in relations between the two nations. At the same time, given that the agreement between India and China (April 29, 1954) would expire on June 3, 1962, the Chinese government proposed that the two counties negotiate a new trade agreement. This proposal, however, was rejected by the Indian government twice, in December 1961 and May 1962. Thus, the Chinese government cancelled commercial agencies in Kalimpong and Kolkata after the agreement expired. Finally, the outbreak of the Sino-Indian war at the end of 1962 directly led to the closure of all traditional trade routes in the Himalayan region except the Zhangmu and Gyirong routes.

After the war of 1962, trade in the Himalayan region mainly focused on the Sino-Nepalese trade routes. Furthermore, the border areas of China and Nepal were successively opened, including ports of Zhangmu, Burang, Riwu-Chentang, Gyirong, and Lizi. According to statistical data from the Ministry of Commerce of China, the trade volume between China and Nepal increased from 204 million US dollars in 2000 to 1.1 billion US dollars in 2018. With increasing demands for regional cooperation and development, the Sino-Indian relationship improved in the 1980s, and some traditional trade routes were reopened. The border trade across the Lipu Lekh pass and Shipki La pass resumed in 1992 and 1993, respectively, followed by the reopening of trade across the Nathu La on July 6, 2006. Nathu La became a new pilgrimage route for India’s official pilgrims in June 2015. In addition, according to our field survey, although a few small-scale trade markets were recovered, they have been almost closed due to the impacts of Sino-Indian relations in recent years. Currently, owing to Indian-controlled Bhutanese diplomacy, the traditional trade routes between Bhutan and China remain closed, except for some small-scale border trades (Zha, 2015). According to our field survey, the small-scale trade markets between Bhutan and China, such as Nyeru in Kangmar, Kuju in Cona, Pagri and Tuna in Yadong, and Se in Lhozhag, faced the same challenges with the Sino-India border due to India’s intervention.

With the rapid development of productivity, an increasing number of people across several tribes and additional pressure on natural resources, people needed to both survive and continue development of the region through the exchange of goods. On the northern side of the Himalayas, livestock farming was well developed and goods such as wool, salt and borax were abundant. On the southern side of the range, grain crops such as rice and wheat were abundant, so people began to meet their basic needs by exchanging salt and grain and gradually formed an interdependent agro-trader-pastoralist economy (Vasan, 2006). In addition, due to the difficulty of accessing these border regions from the mainland on either side, farmers and herders preferred to trade with each other (Karackattu, 2013). Therefore, the exchange of goods that developed to meet people’s basic needs drove the incipient and development of traditional trade routes.

The Tubo Kingdom not only opened the “Ancient Tang-Tibet Road” and “Ancient Tubo-Nepal Road” through Buddhism but also made Kashmir, Bhutan and Sikkim subordinate in the Himalayan region. Mount Kailash and Lake Manasarovar, located in the Ngari Prefecture of Tibet, are regarded as common to the spiritual beliefs by Hinduism, Buddhism, Benjamin and Jainism (Xia, 2004). The people of the Himalayan region have long had a tradition of making pilgrimages to the sacred mountains and lakes through routes such as the Lipu Lekh pass and the Shipki La pass, which serve as both pilgrimages and traditional trade routes.

The Tubo Kingdom unified the Tibetan Plateau and opened up external routes linking Central, South and East Asia with the interior of the Tibetan Plateau. During the period when a strong unified dynasty was established in Central China, an active frontier policy was adopted, great importance was attached to strengthening transport links with the frontier regions, including the Tibetan region, and a system of tribute trade was gradually established to promote the development of routes. Before the 18th century, trade in the Himalayan region was mainly controlled and privileged by merchants from Kashmir and Nepal, with trade concentrated along the Gyirong route and Nyalam route (Xu, 2018). After the Gurkha War of 1791-1793, which was triggered by commercial trade and currency, the Qing government promulgated the Imperially Approved Ordinance for Better Governance of Tibet (the 29-Article Ordinance), standardized border trade, and established tribute relations between the Qing Dynasty and the Himalayan periphery. In contrast, during the decline of successive dynasties and the period when the interior was under multiple regimes, the ability of the Central Plains dynasties to manage within the Tibetan Plateau region was relatively weakened, and the routes were controlled by external forces. From 1912 to 1949, due to domestic political turmoil, the British and other imperialist forces intervened and sabotaged the “independence of Tibet”, trying to block the links between the Chinese mainland and Tibet, control trade routes, and monopolize trade. In 1904, the British invaded Tibet and signed the Treaty of Lhasa, establishing commercial representative offices at the Yadong, Gyantse, and Gartok ports, enjoying trade privileges and using colonial means to gradually explore and control access to the Himalayan region (Zha and Liu, 2014).

Driven by colonial expansion and commercial interests, from Western missionaries to British colonists, they have sought to open land routes to the Chinese mainland. In terms of the way Britain opened routes, first, they reduced production costs by using industrial revolution technologies, growing tea, and exploiting minerals such as borax and salt to replace products from the Chinese mainland. Second, they improved accessibility, reduced transport costs, and enhanced trade between the Himalayan region and the Ganges Plain region by building infrastructures such as railways and roads. Third, they annexed Himalayan countries through war and established the treaty system centred on the British to replace the tribute system centred on China (Li, 2018), control trade routes, and monopolize the trade between the Himalayan region and South Asia. This also eventually led to the Himalayan region trading more closely with South Asia. However, as a result of the World War II, the opening of southern Tibet trade routes was not achieved.

After independence in 1947, India sought to inherit the legacy of British colonization, continued to control traditional trade routes, and monopolized trade in the Himalayan region. Between 1950 and 1962, India imposed two trade controls and embargoed Tibet in China using the control of trade routes (Dai, 2013a; 2013b). At the same time, as India exercised strategic provocation against China, believing that “as long as India did not attack Chinese positions, China would not intervene no matter how many posts and patrols India sent into the territories claimed and occupied by China”, and embarked on a “Forward Policy” (Maxwell, 1981). This eventually led to the Sino-Indian border conflict in 1962, which caused the rapid decline of traditional trade routes.

In the 1980s, some of the traditional trade routes began to reopen as Sino-Indian relations improved. Since 2004, China has been India’s largest source of imports and third- or fourth-largest export market and has become India’s largest trading partner in 2013. India’s exports to China are mostly primary products such as resource products and raw materials, whereas China’s exports to India are mainly labour-intensive manufactured goods, with strong complementarity between the two sides. However, the current trade between India and China is mainly done through the sea route, but there remains potential for the development of land routes in the Himalayan region.

As the Belt and Road Initiative continues to advance, the Himalayan region is receiving increasing attention and importance as a pivot between China and South Asia. China has proposed specific strategies, such as the Bangladesh-China-India-Myanmar Economic Corridor, the China-Pakistan Economic Corridor, the construction of the South Asia Corridor, the China-Nepal-India Economic Corridor and the Trans-Himalayan Economic Corridor. Traditional trade routes in the Himalayan region will be key to the implementation of these strategies. Therefore, the restoration and construction of traditional trade routes will be an opportunity.

At the same time, Nepal and Bhutan are often considered “the proverbial yam sandwiched between two boulders” of China and India (Harris, 2013). The transitional economic dependence of Nepal and Bhutan on India has led to frequent Indian intervention and control of their domestic politics. For this reason, both Nepal and Bhutan wish to break away from their overdependence on India and thus become a bridgehead for economic and cultural development between India and China through the rehabilitation and construction of traditional trade routes in the Himalayan region.