In the 19th century, British railway builders had surveyed the Pangsau Pass, which is 1,136 metres (3,727 feet) high on the India-Burma border, on the Patkai crest, above Nampong, Arunachal Pradesh and Ledo, Tinsukia (part of Assam).
Pada abad ke-19, para pembangun jalur kereta api Britania telah menyurvei Lintasan Pangsau, yang memiliki ketinggian 1.136 meter (3.727 kaki) di perbatasan India-Burma, di puncak Patkai, di atas Nampong, Arunachal Pradesh, dan Ledo, Tinsukia (bagian dari Assam).