Hailar District, formerly a county-level city, is an urban district that serves as the seat of the prefecture-level city Hulunbuir in northeastern Inner Mongolia, China. Hulunbuir, due to its massive size, is a city in administrative terms only, being mainly grassland and rural. Long known as the "Pearl of the Grasslands", Hailar acts as a gateway between China and Russia. The district spans an area of 1,319.8 square kilometers, and has an estimated population of 365,000 as of 2010.