Ishbi-Erra was described as a man of Mari,[i 2] either his origin or the city for which he was assigned. His progress was witnessed in correspondence with the king and between Ibbi-Sin and the governor of Kazallu (Puzur-Numushda, latterly renamed Puzur-Šulgi.) These are literary letters, copied in antiquity as scribal exercises and whose authenticity is unknown.[3] Charged with acquiring grain in Isin and Kazallu, Ishbi-Erra complained that he could not ship the 72,000 GUR he had bought for 20 talents of silver—apparently an exorbitant price—and now kept secure in Isin to other conurbations due to the incursions of the Amorites (“Martu”) and requested Ibbi-Sin supply 600 boats to transport it while also requesting governorship of Isin and Nippur.[i 3][4] Although Ibbi-Sin baulked at promoting him, Ishbi-Erra had apparently succeeded in wrestling control over Isin by Ibbi-Sin's 8th year, when he began assigning his own regnal year-names, and thereafter an uneasy chill descended on their relationship.[5]