Rawalpindi is a city in the Punjab province of Pakistan. It is the fourth most populous city in Pakistan and third most populous in Punjab according to 2017 Census. Rawalpindi is situated close to Pakistan's capital Islamabad, and the two are jointly known as the "twin cities" because of the social and economic links between them. Rawalpindi is on the Pothohar Plateau, and remained a small town of little importance up until 18th century. The Pothohar region was known for its ancient heritage, for instance in the neighbouring city of Taxila, a UNESCO World Heritage Site. In 1765, the ruling Gakhars were defeated and the city came under Sikh rule, Rawalpindi from a small regional town became an important city within the Sikh Empire based at Lahore. The city's Babu Mohallah neighbourhood was once home to a community of Jewish traders who had fled Mashhad, Persia, in the 1830s. The city was conquered by the British Raj in 1849, and in the late 19th century became the largest garrison town of the British Indian Army's Northern command as its climate suited the British authorities. Britain's army elevated the city from a small town to the third largest city in Punjab by 1921. Following the partition of British India in 1947, the city became home to the headquarters of the Pakistan Army.