Yên Bái ( listen) is a city and urban district in Vietnam. It is the capital of the Yen Bai province, in northeastern Vietnam. As of 2003 the district had a population of 78,016. The district covers an area of 58 km².

On 9 February 1930, part of the 4th Regiment of Tonkinese Rifles stationed at mutinied against their French officers in the Yen Bai mutiny. They were suppressed by loyal troops from the same unit. This incident led to widespread disturbances against French rule across northeastern Vietnam during 1930-31.

Yen Bai Online Dien Dan Yen Bai

Coordinates: 21°42′N 104°52′E / 21.7°N 104.867°E / 21.7; 104.867

Yên Bái ( listen) is an agricultural-based province located in Tay Bac, the northern part of northern-central Vietnam. It shares borders with five provinces which are Lao Cai province, Lai Chau province, Son La province, Tuyen Quang province, and Phu Tho province. The province covers an area of 6899.5 square kilometres and as of 2008 it had a population of 750,200 people.

Yen Bai's history is important under the French colony, particularly the subsequent "Yen Bai mutiny", an uprising of Vietnamese soldiers in the French colonial army on 10 February 1930 in collaboration with civilian supporters who were members of the Viet Nam Quoc Dan Dang (VNQDD, the Vietnamese Nationalist Party).

Forestry and farming are the main economic stay of the province. Thac Ba Lake is a natural asset of the country along with its Thac Ba Hydroelectric Plant. Dong Cuong Festival is an important festival of the province.

The province's name derives from Sino-Vietnamese (Hán Tự: 安沛).

According to the General Statistics Office of the Government of Vietnam, the population of Yên Bái province as on 2008 was 750,200 with a density of 109 persons per sqkm over a total land area of 6,899.5 square kilometres (2,663.9 sq mi) of the province. The male population during this period was 372,000 with females accounting for 378,200. There are many ethnic groups in Yen Bai Province. Kin people who form the majority population of the country, settled here long time back and in unison with the local minority tribes established themselves in the region and developed cultivation practices. Kin people’s ancestry is traced to the Hai Duong Pham Ba Luc for nine generations till date and a monument erected in 1937 in Doc village in Hong Commune is highly revered as an ancestral home.