The Edomites were forcefully converted to Judaism, in a Hasmonean sin that bit them and other Jews hard. Herod’s father Antipater was an Idumean his mother was a Nabatean princess. Of course, when the Sanhedrin called him a Roman-imposed foreigner, most were slaughtered. He also killed many members of his family, his wife, and in laws. Nice guy.
As one of the Romans of the time said, it was better to be Herod’s pig than his son.