During the Western Han Dynasty, Su Wu used to herd sheep on the shores of Lake Baikal, and in 1689, the Qing government signed the Treaty of Nebuchu with Russia, and since then it has lost control of Lake Baikal, and the Han people can no longer herd sheep there. When Kangxi signed the Treaty of Nebuchadnezzar with Russia, the boundaries of the eastern region (Heilongjiang region) were clearly demarcated, while the central region (Outer Mongolia) was not clearly demarcated, but the Qing government at that time had sovereignty over about 100,000 square kilometers of land south and southwest of Lake Baikal. In 1727, Yongzheng and Russia signed the Treaty of Kyakhta, and about 100,000 square kilometers of land south and southwest of Lake Baikal belonged to Russia. Since Yongzheng, the Baikal region has been completely occupied by Russia.
In 1689, when the Qing government signed the Treaty of Nebuchu with Tsarist Russia, the Qing government was fighting with Geldan and did not attach importance to negotiations with Tsarist Russia in Nebuchu. Therefore, after the Battle of Yaksa, the Qing government and Tsarist Russia talked about the Treaty of Nebuchadnezzar for three years. In the end, it was the Qing government that made concessions to negotiate the border of the Heilongjiang region, while the border line of the central Mongolian region was to be determined. Without demarcation, Tsarist Russia continued to encroach on Chinese territory. The Qing government negotiated with Tsarist Russia in the hope of delimiting the territory of the middle section as soon as possible, but the Qing government did not heed this proposal. As a result, Yongzheng cut off trade with Tsarist Russia, and the huge caravan of Tsarist Russia could not trade with the Qing government, and finally had to compromise and had to negotiate with the Qing government. This is the origin of the Treaty of Kyakhta, and this time the Qing government made concessions, as we said above, Yongzheng transferred about 100,000 square kilometers of land south and southwest of Lake Baikal to Russia in exchange for peace in the border areas.
To be honest, the ancient rulers of our country were dismissive of the cold Siberian region in the north, they were only interested in the rich land of the Central Plains, and they occupied the Central Plains at all costs, so the ruling class was not at all interested in the cold Siberia. After all, the temperature in Siberia is tens of degrees below zero, and there was no heating in ancient times, and ordinary people could not survive at all. Especially during the Qing Dynasty, we often saw the emperor in the Qing Palace drama, and exiled prisoners to Ningguta. The reason is that Ninguta is close to Siberia, frozen all year round, and the climate is cold. Ordinary people are not willing to live anywhere, so exile of criminals to Ninguta is worse than death for the Central Plains people.
The territory that Tsarist Russia had expanded from the 17th century, especially the Qing government, was fully capable of occupying Siberia in the early days. However, the Qing government regarded the territory of Siberia as a chicken rib, and even if it defeated Tsarist Russia at Yaksa, it was an initiative to negotiate and compromise. Therefore, Tsarist Russia regarded the goodwill of the Qing government as a sign of cowardice and gained inches. If the Qing government could actively send troops to the Baikal region and garrison those places, in fact, Tsarist Russia would not take much advantage. The policy of the Qing government was to exert internal pressure and appease the outside world, so in the face of Tsarist Aggression, it was also a blind compromise, and eventually the Qing government continued to lose territory in the compromise, and eventually degenerated into a semi-colonial and semi-feudal society.