Short answers, pulled from the story.
The name Buriyad appears in The Secret History of the Mongols, possibly written around 1240. This text describes Jochi, the eldest son of Genghis Khan, marching north to subjugate the Buryats in 1207.
Mitochondrial DNA studies reveal about 83.7 percent belonging to Eastern Eurasian origin haplogroups among present-day Buryats. Genetic evidence indicates nearly exclusive East-Eurasian ancestry comprising approximately 95 to 98 percent of total genetic makeup.
Red Army forces crushed the uprising resulting in losses of approximately 35,000 Buryats. Joseph Stalin ordered the killing of over 10,000 Buryats due to fears of nationalism.
Tibetan branch of Buddhism became an official religion in Russia in 1741 when the first Buryat datsan monastery was built. By 1914 there were 48 datsans across Buryatia driving cultural development forward.
The territory was formally annexed to Russia through treaties signed in 1689 and 1727. These agreements separated lands on both sides of Lake Baikal from Mongolia.