 His reign was marked by wars against the Eastern Roman Empire in the west and the Hephthalites in the east, as well as by his efforts and attempts to strengthen royal centralisation in the bureaucracy by imposing Zoroastrianism on the non-Zoroastrians within the country, namely the Christians.His death led to a dynastic struggle between his two sons Hormizd III and Peroz I for the throne, with the latter emerging victorious.Yazdegerd II was the first Sasanian ruler to assume the title of "kay", which evidently associates him and the dynasty to the mythical Kayanian dynasty commemorated in the Avesta.