Analysis of information sources in references of the Wikipedia article "สิบสองจุไทย" in Thai language version.
In the north-western highlands ... the loose federation of Sip Song Chau Tai, the Twelve Tai Cantons, had been formalized around it [Muang Lay (Lai Châu)] since at least the 17th century.
An accord was finally promulgated in July 1948, creating an independent Tai Federation in the Union française, a Federation grouping together the provinces of Lai Chau, Phong Tho and Son La.
