Who is tajik in The Kite Runner?

In "The Kite Runner" by Khaled Hosseini, Tajik refers to a member of the Tajik ethnic group in Afghanistan. One of the main characters, Baba, is a Pashtun, while Hassan, his son's loyal friend and servant, is half-Hazara and half-Tajik. The distinctions between the ethnic groups play a significant role in the novel's themes of social class, discrimination, and loyalty.