In ancient times the two clans were repeatedly joined by marriage.
Tips
usage
媾 is literary. The reading you will actually meet is 媾和 ('to sue for peace, make terms'). Its other senses, intermarriage and sexual union, are classical and now rare.
女 is the woman radical. The earliest sense was marriage joining two families through a woman, which is why the kinship and union meanings sit under this radical.
