Tibetan chronicles of Ladakh, dating back to the 7th century. have the first mention of the territory of Lo. Then it was under the control of the Tibetan governors, whose residence was in Tsarang. The son of the governor, Ame Pal, in 1440 took advantage of the low control of the Tibetan state and declared the territory of Lo an independent kingdom. The Monastery of Tsaranga contains the book of Mola, which describes the history of the formation of the state of Lo. The main character is the unifying king Ame Pal. For almost 100 years, the aggressors did not touch the kingdom of Lo, during which time general prosperity came. It is worth mentioning that the climate was then mild and the land bore better. Under the leadership of Ame Pal, the territory of Law was large, he ordered the construction of fortresses and monasteries at strategic points.
The most famous fortress is Dzong Kecher, which is located on a narrow ridge near Lo Montang. The main figure for the fortresses of that time was a rectangle, but Kecher is an exception. According to legend, the father of Ame Pal, who is the governor of Lo, ordered Ame Pal to build a fortified fortress in this area and protect it from the cruel Demon Prince "Black Monkey", who was establishing his order at the source of the Kali-Gandaki River. Built by Ame Pal, one of the corners pointed to the gate of the fortifications of the "Black Monkey", which caused his displeasure, because it was sending invisible ominous arrows. However, the alteration of Ame Pal, which made the walls round, did not help the Demon, literally a couple of years later his fortress was broken and destroyed.
According to another legend, Ame Pal chose the place for the construction of the capital based on observations of goats. After he decided to move his residence from Tsarang, he prayed all night, and in the morning he took a herd of goats and went where they showed the way. Where they stayed, he founded the capital - this place was located near the Kecher fortress. It is for this reason that the head of a goat serves as a symbol of the city. The modified name Lo-Mantang turned into Mustang, apparently for cartographers this word was more familiar.