Although Mesopotamia had been acquired by the Ottoman Empire in 1555 by the Peace of Amasya, until the Treaty of Zuhab in 1639 Ottoman control over Mesopotamia was not decisive. After the Peace of Amasya, the Safavids recaptured most of Mesopotamia one more time during the reign of king Abbas I (r. 1588–1629). Amongst the newly appointed Safavid governors of Mesopotamia during those years was Qasem Sultan Afshar, who was appointed governor of Mosul in 1622. Prior to 1638, the city of Mosul was considered to the Ottomans "still a mere fortress, important for its strategic position as an offensive platform for Ottoman campaigns into Iraq, as well as a defensive stronghold and staging post guarding the approaches to Anatolia and to the Syrian coast. Then, with the Ottoman reconquest of Baghdad (1638), the liwa of Mosul became an independent wilaya."