Muang Then is a legendary Tai locality believed to be associated with modern-day Điện Biên Phủ, Vietnam. [1][2]
In legend, it is significant as the initial settlement of Tai people migrating southward from Yunnan around the time of the Kingdom of Nanzhao under their leader Khun Borom, who is associated[1] with Piluoge (ruler of Nanzhao from 728-748).