Upi/upija was an ancient Babylonian city near the River Tigris identified with Tall al-Mujailāt /Tulūl al-Mujaili mound.
See:
- Peter Högelmann and Kai Buschmann, "Östlicher Mittelmeerraum. Das achämenische Westreich von Kyros bis Xerxes (547–479/8 v. Chr.)," in Tübinger Atlas des Vorderen Orients, B IV 23, 1986.