Mongolian is an Altaic language and is the official language of Mongolia and both the most widely spoken and best-known member of the Mongolic language family. It is spoken by approximately 5 million people in Mongolia, China, Afghanistan and Russia. There are a number of closely related varieties of Mongolian: Khalkha or Halha, the national language of Mongolia, and Oirat, Chahar and Ordos, which are spoken mainly in the Inner Mongolian Autonomous Region of China.
Other languages considered part of the Mongolian language family, but separate from Mongolian, include Buryat and Kalmyk, spoken in Russia and Moghul or Mogul, spoken in Afghanistan.
In 1208 Chinggis Khan defeated the Naimans, Turkic tribes living in Central Asia, and captured their Uyghur scribe Tatar-Tonga, who apparently adapted the Old Uyghur alphabet to write Mongolian. The alphabet created by Tatar-Tonga is now known as the Uighur/Uyghur Script, the classical or traditional Mongol Script, the Old Script, or Mongol Bichig in Mongolian.
In Mongolia, Khalkha Mongolian is predominant, and is currently written in both Cyrillic and the traditional Mongolian script. In Inner Mongolia, it is dialectally more diverse and written in the traditional Mongolian script. However, Mongols in both countries often use the Latin script for convenience on the Internet.
In Inner Mongolia, official language policy divides the Mongolian language into three dialects: Southern Mongolian, Oirat, and Barghu-Buryat. Southern Mongolian is said to consist of Chakhar, Ordos, Baarin, Khorchin, Kharchin, and Alasha. The authorities have synthesized a literary standard for Mongolian in whose grammar is said to be based on Southern Mongolian and whose pronunciation is based on the Chakhar dialect as spoken in the Plain Blue Banner. Dialectologically, however, western Southern Mongolian dialects are closer to Khalkha than they are to eastern Southern Mongolian dialects: e.g. Chakhar is closer to Khalkha than to Khorchin.