 After a prolonged struggle they were forced to conclude a peace, and their king Grumbates accompanied Shapur II in the war against the Romans.Grumbates thus participated in the Siege of Amida in 359 CE as an ally of Shapur II.His participation to the Sasanian campaign in the Eastern Caspian lands are described by Ammianus Marcellinus, who was inside the fortress of Amida at the time