Kulachi, from Kolanch.

Kulachi is probably from the Kolanch Valley in Mekran. This tribe, once

powerful, but now of small importance, has left its name on the map. The town
of Kulachi, in Dera Ismail Khan, though now belonging to the Gandapur
Afghans, bears it, and the great seaport of KarachI has the same name, with the
usual SindhI change of ‘l’ to ‘r’.