The far north-west of the sheet: the Nậm Rốm plain of Mường Thanh, the largest flat ground in these mountains, with Mường Lay on the Đà and the border hills towards Muang Phuan and Yunnan.
Wet-rice valleys under Tai lords, hill peoples above them. It looks to Yunnan and the Lao muang at least as much as to Thăng Long (board). The Tai Dam chronicle (Quam To Muong) and the Muong origin tales were written down centuries after 1200; we read them as a guide to the ground, not as dated evidence.
Who holds it
- Title
- Tai chao muong (valley lords) and their kin
- Confidence
- low
Tai chronicles and Vietnamese notices as reported second hand; board
Overlord
Thăng Long claims tribute in name when strong (board); Dali's reach down this far is for the Yunnan researcher to write.
How things stand that morning
Not pinned; no dated record.
Wealth
Wet rice, cattle, salt and iron traded in, forest goods.
Military
Valley levies; no numbers.
Threats
- Feud between muong
Places of note
- Muong Thanh: Chief basin
Where the sources disagree
Evidence: The campaign board entry description and a polygon built from modern districts; nothing in our sources dates the unit to 1200.
"The campaign board" is OMNIA's working map. These notes record where its earlier claims were checked against the sources.
On the map: A union of modern districts standing for the country; the real edge was not a line (a raiding belt or a day's walk of hills).
Primary sources for Tai and Muong of the north-west
Chronicles, registers, sagas and inscriptions written in or near 1200 that cover this entry. Each has its own page with editions, translations and where to read it.
- The Complete Annals of Dai Viet, Ngo Si Lien, drawing on Le Van Huu's Dai Viet su ky (1272) and Phan Phu Tien; continued by Pham Cong Tru and Le Hi (1479; printed 1697 in the standard Chinh Hoa edition). The main narrative source for Dai Viet in 1200, compiled in 1479 from Le Van Huu's lost history of 1272. Read online
- The Unofficial History of Nanzhao, Yang Shen; revised by Hu Wei (16th century, revised 1775, from Dali and Yunnan traditions and lost local histories). The kingdom of Dali has no surviving text of 1200: its own records were destroyed in the Mongol conquest and after, and the Song shi's Dali entry ends in 1175. Read online
Sources and studies
- OMNIA board notes for the Vietnam and Champa area (a lead, not a source)
Last revised 4 November 2026. Published 4 November 2026. Suggest a correction on the OMNIA Discord.