Arkhangai aimag was formed from parts of the Tsetserleg Mandal Uulyn aimag in 1931. At that time, the aimag had 35 sums, 65,333 inhabitants in 22,285 households, and 1,800,000 head of livestock. The aimag center Tsetserleg was established at the site of the Zaya Khüree monastery, which had been first founded in 1586.our aimag has got many rivers.The rivers are Chuluut, Khanui, and Tamir have their origins in the valleys of the Khangai Mountains. Together with some smaller tributaries they all belong to the watershed of the Selenge. The Orkhon also traverses the eastern end of the aimag for a short stretch.
The lake Terkhiin Tsagaan Nuur is located in the west. According to a legend it was created when a giant took a large rock and threw it away. Looking back he saw a white surface and exclaimed in surprise, "Look, a white lake!" The exclamation has become the name of the lake. The rock ended up farther to the east and is called Taikhar Chuluu. The small lake Ögii Nuur is located in the eastern part of the aimag in the Sum of the same name.our aimag is very beautiful nature.