In the novel The Kite Runner, there is a description related to this. "Ali and Hassan are Hazaras and have a typical Mongolian appearance ... They (Hazaras) are descendants of Mongols, slightly similar to China."
Hazaras are descendants of Mongols. If the above is just speculation, then genetic verification confirms this. A genetic test by Oxford geneticist Sykes confirmed that one third of Hazaras in Afghanistan carry Mongolian genes.