 After this defeat, Yazdegerd fled deeper into Media.He subsequently raised a new army and send it to Nahavand to retake Ctesiphon and prevent any further Muslim advances.The army that Yazdegerd sent seemed such a serious threat that it led Umar to combine the Arab forces of Kufa and Basra under Al-Nu'man ibn Muqrin and send them against the Sasanians with reinforcements from Syria and Oman.