What is "achakzai"

Achakzai , pronounced in Pashto, is a Pashtun tribe basically that resides on both sides of current Pak-Afghan border. The tribe has two main sub-castes first Gujanzai and second Badinzai and there many several sub castes and each caste has its own elder, Khan or Malak. The Bollywood actor Salman Khan and his family claim to belong to this tribe of Pashtuns.