Rivalry between Nepal and the East India Company—over the princely states bordering Nepal and India—eventually led to the Anglo-Nepalese War (1814–16). The Treaty of Sugauli was signed in 1816, ceding large parts of the Nepali territories of the Terai and Sikkim , which accounted to nearly one-third of the country, to the British in …

https://en.wikipedia.org/wiki/Kingdom_of_Nepal