The Byzantine–Sasanian Wars of 572–591 and 602–628 produced the cumulative effects of a century of almost continuous conflict, leaving both empires crippled. When Kavadh II died only months after coming to the throne, Persia was plunged into several years of dynastic turmoil and civil war. The Sasanians were further weakened by economic decline, heavy taxation from Khosrau II's campaigns, religious unrest, and the increasing power of the provincial landholders. The Byzantine Empire was also severely affected, with its financial reserves exhausted by the war and the Balkans now largely in the hands of the Slavs. Additionally, Anatolia was devastated by repeated Persian invasions; the Empire's hold on its recently regained territories in the Caucasus, Syria, Mesopotamia, Palestine and Egypt was loosened by many years of Persian occupation. Neither empire was given any chance to recover, and according to George Liska, the "unnecessarily prolonged Byzantine–Persian conflict opened the way for Islam".