Where does the word Mongolia originated?

The origin of the name “Mongolia” is commonly traced to the Mongolic tribal confederation and its ruling clan known as the Borjigin, which established numerous nomadic empires beginning with the Mongol Empire in the 13th century. The term likely evolved from the Mongolian word "Mongol", meaning "eternal", "fierce", or "brave".

Other theories suggest that the name may derive from the Mohe people of Northeast Asia, who were sometimes called "Mongu" by the Khitans. Another possible origin is the Mongolian word "Mongγol-u ulus" meaning "Mongol nation".