Yên Bái is a city and urban district in Vietnam
. It is the capital of Yên Bái Province, in the Northeast region of Vietnam.The district covers an area of 58 km sq.On 9 February 1930, part of the 4th Regiment of Tonkinese Rifles stationed at Yen Bai mutinied against their French officers in the Yên Bái 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.