Which feral horse is a rare species that can only be found in limited numbers in Mongolia and China?

The feral horse which is a rare endangered species that can only be found in limited numbers in Mongolia and China is the modern Przewalski's horse. These feral horses are now considered untamed descendants of subspecies of domesticated horses. They're not truly “wild" horses, but merely domesticated horses that haven't been tamed.

Genetics research has accordingly determined that Przewalski’s horses (species with 66 chromosomes, compared to 64 in all other horses) can be traced to horses domesticated by the ancient Botai culture of Central Asia. The Botai domesticated their horses, truly wild horses which surrounded the homes of the Botai on the Eurasian steppe between 3700-3100 BCE. The horses (Przewalski’s horses) were part of the natural ecosystem and became a natural resource for the Botai.

Today, Przewalski’s horses have been reintroduced to conservation areas in Russia as well as Mongolia and China. A population of Przewalski’s horses has also been successfully introduced to the isolated, radioactive exclusion zone surrounding the Chernobyl Nuclear Power Plant in Ukraine and Belarus.