Origin of the Kochi people (Pashtun nomads)?

http://en.wikipedia.org/wiki/Kochi_people

Kochis or Kuchis (from the Persian word: کوچ koch; meaning "migration") are Afghan Pashtun nomads, primarily from the Ghilzai tribal confederacy. Some of the most notable Ghilzai Kochi tribes include the Kharoti, Andar and Ahmadzai. Sometimes Durrani tribes can be found among the Kochi, and occasionally there may also be some Baloch people among them that live a pastoral nomadic lifestyle.

ok, lol, "koch" is derived from Turkic. So who are these Kochis?