Gargareans

In Greek mythology, the Gargareans (or Gargarenses, Γαργαρείς) were an all-male tribe. They had sex with the Amazons annually in order to keep both tribes reproductive. Varying accounts suggest that they may have been kidnapped, raped, and murdered for this purpose, or that they may have had relations willingly. The Amazons kept the female children, raising them as warriors, and gave the males to the Gargareans.