Where are the mongols originally from? your central asia east asia the middle east europe

The Mongols were a nomadic tribe to the north of China. They shared the mountainous areas between China and Siberia with many other such tribes, many of them Turkic. 

When Ghengis Khan united them as a powerful nation with a mighty army of mounted archers they were irresistible for all but might walled cities. But they were fractious, even within the family so when Ghengis died they split into four nations, albeit ruling most of Asia.

I believe it in-between both central-east Asia

You can make up your decision after reading to what I have written

For it's up to you either central Asia or east Asia