Shapur II
In the winter of 357–58, Constantius received ambassadors from Shapur II who demanded that Rome restore the lands surrendered by Narseh. Despite rejecting these terms, Constantius tried to avert war with the Sassanid Empire by sending two embassies to Shapur II. Shapur II nevertheless launched another invasion of Roman Mesopotamia. In 360, when news reached Constantius that Shapur II had destroyed Singara (Sinjar), and taken Kiphas (Hasankeyf), Amida (Diyarbakır), and Ad Tigris (Cizre), he decided to travel east to face the re-emergent threat.