Opis was an ancient Near East city near the Tigris, not far from modern Baghdad. The equivalence of Opis and Upi are now usually assumed but not yet proven. Early on it was thought that the ideogram for Upi might refer to Kesh or Akshak. Its location is not yet known with certainty though Tall al-Mujailāt has been proposed. That site has also been suggested as the location of the ancient city of Akshak.