Following the defeat of Belisarius in the Battle of Callinicum (19 April 531), Sittas replaced him in the leadership of the forces in the east. During the Siege of Martyropolis (531), Sittas and Al-Harith ibn Jabalah camped at the nearby city of Amida, but avoided engagement as the Persians had the upper hand there. Kavadh, however, died within the year, and his son and successor Khosrau I (r. 531–579 AD) was interested in stabilizing his internal position for the time being and started negotiations for a peace. The "Eternal Peace" agreement (which eventually lasted ten years) was signed on September 532 on the terms of all Byzantine land lost under Emperor Justinian's rule to be returned, and the Byzantines to pay heavy tribute in exchange for peace. The country of Iberia remained under Sassanid control.