The clan started when Shigehira KOBAYAKAWA gave his fourth son Masakage KOBAYAKAWA a part of the estates of the Tsuunosho and Takeharanosho which he received after the Jokyu War and Nutanosho Nashi-go village, and Masakage settled in the Kimura-jo Castle.
小早川茂平が、四男・小早川政景に、承久の乱に得た都宇・竹原荘、沼田荘梨子羽郷の一部を分与し、木村城を本拠としたのが始まりである。