Hulunbuir or Hulun Buir is a region that is governed as a prefecture-level city in northeastern Inner Mongolia, in China. Its administrative center is located at Hailar District, its largest urban area. Major scenic features are the high steppes of the Hulun Buir grasslands, the Hulun and Buir lakes (the latter partially in Mongolia), and the Khingan range. Hulun Buir borders Russia to the north and west, Mongolia to the south and west, Heilongjiang province to the east and Hinggan League to the direct south. Hulunbuir is a linguistically diverse area: next to Mandarin Chinese, Mongolian dialects such as Khorchin and Buryat, the Mongolic language Dagur and some Tungusic languages are spoken there.
During the Han Dynasty (206 BCE–220 CE), Hulunbuir was part of the Liaodong Commandery. During the Qing Dynasty (1644–1912), Hulunbuir was part of Heilongjiang province. The 1858 Treaty of Aigun established today's approximate Sino-Russian border, at a great loss to Heilongjiang's territory. In 1901, the Chinese Eastern Railway linked Hulunbuir to the rest of northeast China and to Russian Far East. From 1912-1949, during the Republic of China (ROC) period, Hulunbuir was part of Xing'an and Heilongjiang provinces. A treaty between the Russian Empire and the ROC on November 7/October 24, 1915 designated Hulunbuir a "special" region under Chinese sovereignty, but in practice Russia had partial control over day-to-day administration. In 1929, the Soviet Union broke this agreement and invaded Hulunbuir. After the Japanese occupation of China, Hulunbuir became part of the Japanese puppet state Manchukuo, which was not recognized by the Chinese. In the Chinese Civil War, the Communist Party of China gained the support of Inner Mongol leaders like Ulanhu by promising the irredentist expansion of Inner Mongolia into areas that had majorities of Han and Manchu peoples.
After the 1949 Communist revolution, Hulunbuir was annexed into Inner Mongolia, but the region kept economic ties to the rest of the northeast via the Chinese Eastern Railway.During the Cultural Revolution, the parts of historical Manchuria inside Inner Mongolia were briefly restored to their original provinces; Hulunbuir was given back to Heilongjiang from 1969 to 1979. Until October 10, 2001, Hulunbuir was administered as a League. The area is 263,953 km2 (101,913 sq mi) and had a population of 2.710 million in 2004, while the gross domestic product was RMB 21.326 billion. The jurisdiction area of the city is larger than all but 8 Chinese province-level divisions (and 42 U.S. states), although the actual urban agglomeration is just a very small part of the region, and the average population density of the area is very low.
Hulunbuir itself (Hailar) has a subarctic climate (Köppen Dwc). Winters are long, very dry and severe, due to the semi−permanent Siberian High, while summers are short, though very warm, and rather wet, due to the East Asian monsoon. At Hailar, the monthly 24-hour average temperature ranges from −25.1 °C (−13.2 °F) in January to 20.0 °C (68 °F) in July, while the annual mean is −0.96 °C (30.3 °F). With at least 55% of possible sunshine in all months and an annual total greater than 2,700 hours, sunny weather dominates year-round. Approximately 70% of the annual rainfall occurs during the three summer months.