People always say that China's modern history is a history of humiliation, because China has lost too many national rights and lost too much land in modern history, and some of the lost land has become an eternal pain in the hearts of the Chinese people.
There is such a country. The total area of this country is 170,000 square kilometers, but 160,000 square kilometers of it is Chinese territory.

Tangnu Ulianghai
This country is the Republic of Tuva. It is now one of the union republics of Russia, with a total area of 170,000 square kilometers. And this 160,000 square kilometers of China’s homeland is the Tangnu Ulianghai area.
The current Tangnu Ulianghai area is roughly located at the junction of Mongolia and Russia.
Tangnu Ulianghai has become the territory of China during the Tang Dynasty . During the Tang Dynasty, Tangnu Ulianghai was inhabited by Doubo people, and the Doubo people established a vassal relationship. The Tang Dynasty also established the Anbei Protectorate to manage the Tangnu Ulianghai area.

The location of Tangnu Ulianghai
In the 13th century AD, Genghis Khan unified all Mongolian tribes, which naturally included today's Tangnu Ulianghai area. Later, Kublai Khan, the grandson of Genghis Khan, marched southward, unified the entire land of China, and established the Yuan Dynasty. At this time, Tangnu Ulianghai, as a part of Mongolia, was closely integrated with the land of China.
In the 17th century AD, the Manchus once again unified the country and established the Qing Dynasty . The Manchu and Qing Dynasty regime established a complete local governance system in the Tangnu Ulianghai area. The Qing Dynasty conducted detailed management of Tangnu Ulianghai. The region's trade, law, administration, population, etc. were all under the jurisdiction of the central government.

Tangnu Ulianghai Region
However, by the end of the Qing Dynasty , the Qing government became increasingly corrupt and incompetent, and China had fallen behind the world's development trend. In the north of China lies an ambitious country - Tsarist Russia.
Tsarist Russia was very interested in China's territory, so it formulated a "Yellow Russia Plan". In this plan, Tsarist Russia even wanted to annex the entire territory of China except Shanhaiguan.
During the Second Opium War , Tsarist Russia took advantage of the situation and occupied large areas of northwest and northeastern China. However, Tsarist Russia was not satisfied with the status quo.

In 1911, the Revolution of 1911 broke out in China. The struggle between various forces in China was very serious, and Tsarist Russia took the opportunity to instigate Mongolian independence. After Mongolia became independent, the Beiyang government began sending troops to regain Mongolia. After three years of war, China only regained Inner Mongolia, while Outer Mongolia and the Tangnu Uryanghai region remained independent.
In 1917, when the revolution broke out in Russia, the Beiyang government once again sent troops to recover the Tangnu Ulianghai area. However, under the planning and manipulation of Soviet Russia, Tangnu Ulianghai held a referendum, and the result was that the Tangnu Ulianghai region established an independent country, and a Tuva Republic was established.

Tangnu Ulianghai scenery
As a result, Tangnu Ulianghai left the embrace of his motherland, and the Republic of Tuva soon joined the Soviet Union and became a republic of the Soviet Union. Later, after the disintegration of the Soviet Union, the Republic of Tuva became a member of the Russian republics.