Muang Then is a legendary Tai locality believed to be associated with modern day Dien Bien Phu

Dien Bien Phu

Điện Biên Phủ is a city in northwestern Vietnam. It is the capital of Dien Bien province, and is known for the events there during the First Indochina War, the Battle of Dien Bien Phu, during which the region was a breadbasket for the Việt Minh.-Population:...

, Vietnam

Vietnam

Vietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –...

. In legend, it is significant as the initial settlement of Tai people migrating southward from Yunnan

Yunnan

Yunnan is a province of the People's Republic of China, located in the far southwest of the country spanning approximately and with a population of 45.7 million . The capital of the province is Kunming. The province borders Burma, Laos, and Vietnam.Yunnan is situated in a mountainous area, with...

 around the time of the Kingdom of Nanzhao under their leader Khun Borom

Khun Borom

Khun Borom Rachathirath is the legendary progenitor of the Tai-speaking peoples, considered by the Lao and others to be the father of their race....

, who is associated with Piluoge (ruler of Nanzhao from 728-748).