From the Wikipedia page 
Zabaykalsky Krai (Russian: Забайкальский край, tr. Zabaykalsky kray; IPA: [zəbɐjˈkalʲskʲɪj kraj], lit. Transbaikal krai) is a federal subject of Russia (a krai) that was created on March 1, 2008 as a result of a merger of Chita Oblast and Agin-Buryat Autonomous Okrug, after a referendum held on the issue on March 11, 2007. The administrative center of the krai is located in the city of Chita.
The krai is located within the historical region of Transbaikalia and has extensive international borders with China (998 km) and Mongolia (868 km); its internal borders are with Irkutsk and Amur Oblasts, as well as with the Republic of Buryatia and the Sakha Republic.