Muang Then

{{Notability|date=December 2011}}

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. {{cite book|last=Jumsai|first=M.L. Manich|title=History of Laos|date=1967-08-05|isbn=978-974-7390-21-6}}{{cite book|last=Ratanavongsa|first=Prince Phetsarath|title=The Iron Man of Laos|date=1978|publisher=Dalley Book Service, Inc.}}

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 with Piluoge (ruler of Nanzhao from 728 to 748).