On 1 March 2008, the region merged with Chita Oblast (which it was surrounded by) to form the new Zabaykalsky Krai.

The territory of the former ABAO is now the Agin-Buryat Okrug of Zabaykalsky Krai, in which it has a special status.

The district was first created in its modern form on 26 September 1937 as the Agin Buryat-Mongol National Okrug within Chita Oblast.

Following the change of the ethnonym "Buryat-Mongol" to "Buryat" on 16 September 1958, the region was renamed to Agin-Buryat National Okrug, and became the Agin-Buryat Autonomous Okrug" on 7 October 1977.

[1][2] Work on merging the region with Chita Oblast began in April 2006.