The first traces of human presence in the area dates to 35 to 150 thousand years ago. Early evidence was found on the surface of ancient river gravels Gyrshelunki (tributary of the Khilok River) near the city of
Chita, near
Ust-Menza on the Chikoy River. Based on toponyms, Zabaykalsky might have once been inhabited by a non documented, extinct
Yeniseian language. Mongolic-related
Slab Grave cultural monuments are found in
Baikal territory. The territory of Zabaykalsky Krai has been governed by the
Xiongnu Empire (209 BC-93 CE) and Mongolian
Xianbei state (93-234),
Rouran Khaganate (330–555),
Mongol Empire (1206–1368) and
Northern Yuan (1368–1691). Medieval Mongol tribes like
Merkit,
Tayichiud,
Jalairs and
Khamag Mongols inhabited in the krai. In the 17th century, some or all of Mongolic-speaking
Daurs lived along the
Shilka, upper
Amur, and on the
Bureya River. They thus gave their name to the region of
Dauria, also called Transbaikal, now the area of
Russia east of
Lake Baikal. Today
Buryat-Mongols remained in the territory of the krai. Preliminary work on the unification of the Chita Oblast and Agin-Buryat Autonomous Okrug was started at the level of regional authorities in April 2006. The governor of Chita Oblast Ravil Geniatulin, mayor of the Agin-Buryat Autonomous Okrug Bair Zhamsuyev, head of the regional parliament Anatoly Romanov, and Dashi Dugarov sent a letter to the president of Russia, Vladimir Putin, and on 17 November 2006, he supported the initiative. A referendum on unification took place on 11 March 2007. In Chita Oblast, "yes" was the predominant answer to the following question: In Chita Oblast, 90.29% (535,045 voters) of the voters voted for the union versus – 8.89% (52,698 voters) who voted against it. 72.82% of the electorate participated. In the Aga Buryat Autonomous Region 94% (38,814 voters) voted for the union versus – 5.16% (2129 voters). 82.95% of the electorate voters participated. On 23 July 2007,
Russian president Vladimir Putin signed a federal constitutional law "On Establishment in the Russian Federation of a new subject of the Russian Federation in the merger of Chita Oblast and Agin-Buryat Autonomous Okrug", adopted by the
State Duma on 5 July 2007. and approved by the
Federation Council on 11 July 2007. ==Administrative divisions==