Because Takakage's Kobayakawa clan and Motoharu's Kikkawa clan supported the Mori clan, which was their head family, the two clans were called Mori Ryosen.
隆景の小早川氏と元春の吉川氏の両家が、本家である毛利氏を支えたことから、両家は毛利の両川と呼ばれた。