Sơn La Province in the context of Tây Bắc

Tây Bắc (literally "Northwest") is one of the regions of Vietnam, located in the mountainous northwestern part of the country. It consists of four provinces: Điện Biên, Lai Châu, Sơn La and Lào Cai. It has a population of 4.9 million (2022) and it is fully landlocked.

Điện Biên is a province in the Northwest region of Vietnam. It is bordered by Lai Châu to the northeast, Sơn La to the southeast, Pu'er City, Yunnan, China, to the northwest, and Phongsaly province in Laos to the west. The province covers an area of about 9,540 km (3,683 mi) and as of 2024 it had a population of 656,700 people.

Mường (thiếng Mươ̒ng; Vietnamese: tiếng Mường) is a group of dialects spoken by the Mường people of Vietnam. They are in the Austroasiatic language family and closely related to Vietnamese. According to Phan (2012), the Mường dialects are not a single language, or even most closely related to each other, but rather are an ethnically defined and paraphyletic taxon.

Mường dialects are primarily spoken in mountainous regions of the northern Vietnamese provinces of Hòa Bình, Thanh Hóa, Vĩnh Phúc, Yên Bái, Sơn La, and Ninh Bình.