Most of the Western regions of China like the territories Xingjiang, Inner mongolia, Tibet and provinces of central China are sparsely populated, they are either deserts, plateaus or uninhabitable terrains. It is easy to defeat these territories which have less resources and can field weak armies,
well, they are quite strong in their terrains since the logistic is a huge problem for army from central area of China at that time.
So, we decided to solve those problems at once.
1.Zunghar Genocide (80% Oirat Mongols killed and 20% fled to Russia)1757
2.Extermination of the Jinchuan Tibetan people in 1776
Did China ever managed to rule Mongolia, the opposite happened.
Mongolia grassland was ruled by Huns then Turks and finally Modern Mongols.
Why do you think Huns and Turks fled to Europe?
Chinese hans live in eastern parts of todays china the western regions have natural barriers which protected them from S.Asia and central Asia.
1. central Asia: We keep trying to expand towards Middle East since Han empire until lose to Arabic empire (in central Asia close to Iran) at Tang Dynasty. Central Asia started to islamic from that time, but now you still can see buddha statues at there.
2. South Asia:
Wang Xuance
Wang Xuance - Wikipedia, the free encyclopedia
Wang Xuance (Chinese: çŽ‹çŽ„ç– (pinyin wáng xuáncè), fl. 7th century) was a Tang Dynasty guard officer and diplomat. In 648, Tang Taizong sent him to India in response to Harshavardhana sending an ambassador to China. However once in India he discovered Harshavardhana had died and the new king attacked Wang and his 30 mounted subordinates.[1]
This led to Wang Xuance escaping to Tibet and then mounting a joint of over 7,000 Nepalese mounted infantry and 1,200 Tibetan infantry and attack on the Indian state on June 16. The success of this attack won Xuance the prestigious title of the "Grand Master for the Closing Court."[2] He also secured a reported Buddhist relic for China.[3]
Harsha - Wikipedia, the free encyclopedia
Arjua the king of Harshavardhana was capture alive and sent back to the capital of Tang empire. him was killed a few days after for his crime.