<Ul> <Li> 1204--The Sack of Constantinople by the Fourth Crusade </Li> </Ul> <Li> 1204--The Sack of Constantinople by the Fourth Crusade </Li> <Li> The final decline during the Byzantine--Ottoman Wars . </Li> <P> In the 5th--7th century, the Eastern Roman or Byzantine Empire was a continuation of the Roman Empire . The loss of the Western territories in the 5th century led to the loss of some important cities such as Rome . The creation of the Germanic states of the Franks, Visigoths, Ostrogoths and later of the Lombards out of the rubble of the Western Roman Empire meant that in time they would seek to challenge the authority of the Eastern Roman Empire . General Flavius Belisarius under Justinian I in the early 6th century made a serious attempt to recover the western half; however his gains were short - lived and poorly planned out--resources and troops that could have been used to defeat the Persians were diverted forcing the Byzantines into tribute and diplomacy to deal with this Eastern threat . The loss of the western territories led to the Patriarch of Rome achieving greater independence from Byzantium, which no longer provided adequate protection to the Pope . Consequently, the Holy See and Byzantium would have disagreements, culminating in the schism of 1054 and the disaster of the Fourth Crusade in the 13th century . </P>

Three reasons for the final decline of the byzantine empire