India and China share about 3,488 km long International Boundary, which has three sectors: Western, Middle and Eastern. The Eastern sector comprises two Northeastern states, that is, Arunachal Pradesh measuring 1,124 kms and Sikkim measuring 219 kms, respectively. Due to recent changes in the geopolitical relationship with China, border management and transport infrastructure development have occupied centre stage. In recent years, the Government of India has taken initiatives to develop railway infrastructure in Northeast India. The study will focus on the role of railway transportation in Sino-Indian geopolitical competition. The study is based on secondary data collected from the office of General Manager, Northeast Frontier Railway, the Census of India and reports of Memorandums of Understanding between India and China. The study reveals that railway infrastructure along the border creates geo-psychological pressures on both countries, influencing the divergent geopolitical relationship between India and China. Railway diplomacy is a tool kit of critical geopolitics which reveals the contours of geopolitical competition in borderlands.