Mongolia's only valuable asset is its mines, which can only be sold cheaply to China. Because it has no ports, it has only two neighbors, and the other neighbor, Russia, is also a country that sells ore to China.
For us Chinese, we get what we want whether Mongolia is an independent country or not.
And if Mongolia becomes a Chinese territory, we need to consume the central treasury to alleviate poverty in Mongolia, we have to employ Mongolians at Chinese wage levels (Mongolians are paid less than one-tenth of Chinese workers), and we have to help Mongolia to treat its desertified grasslands. This group of Mongolians may also bring separatist terrorists and bring chaos to our society.
So you tell us, why are we going to annex Mongolia? Just for the map?