Various estimates put the population of Pagan Empire as anywhere between one and two and a half million but most estimates put it between one and a half and two million at its height. The number would be closer to the upper end, assuming that the population of pre-colonial Burma remained fairly constant. (The size of population in medieval times tended to stay flat over the course of many centuries. England's population between the 11th and 16th centuries remained at around 2.25 million, and China's population until the 17th century remained between 60 and 100 million for 13 centuries.) Pagan was the most populous city with an estimated population of 200,000 prior to the Mongol invasions.