As land transportation occupies a great deal of the Belt and Road Initiative (BRI), the railway plays an indispensable role. After a few years of development, BRI rail projects have connected China and its various neighbours. Through those rail lines, the second largest economy in the world is likely to affect the neighbouring countries and consequently reshape the geopolitical landscape. However, different rail gauges and the presence of rival great powers, namely Russia and India, as well as other external technology providers, constrain China’s rail expansion in Mongolia and Central Asia. In Southeast Asia, Beijing faces more favourable conditions. There are few great powers to obstruct Beijing in the subregion, and there is demand for separated rail systems of the standard gauge variety. However, the centrepiece of rail planning in Southeast Asia, the Singapore-Kunming Rail Link (SKRL), has not progressed well, probably due to the reasons of costs, affordability, and low public dependence on rail. Although the BRI rail projects may not consistently be a game changer for China’s geopolitical ambitions, they have inspired other regional countries, especially the landlocked ones, to develop strategic connections, whether with Chinese involvement or not.