"Herodian tells graphically how Domna used every means she had, including tears, in an attempt to prevent one solution, the geographical division of the Empire, west and east, between the brothers, with Caracalla receiving the west (including the North African provinces up to Greek speaking Cyrenaica) and Geta the east, with Alexandria or Antioch as his capital, the Senators were to divide according to their origins."
Julia Domna by Barbara Levick