Muang Thaeng or Mường Thèn is a legendary Tai locality believed to be associated with modern-day Mường Thanh Valley in Điện Biên province of Vietnam. ^[1][2]

In legend, it is 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 to 748).