Which evidence best supports the historical claim that the East-West Schism did not begin in 1054 CE, but that the mutual excommunication was part of an already growing division?

Question

Which evidence best supports the historical claim that the East-West Schism did not begin in 1054 CE, but that the mutual excommunication was part of an already growing division?

The Byzantine Empire rose as a major economic and political power in the western Mediterranean region while Western Europe became more
isolated.

Crusaders from Western Europe looted and sacked the city of Constantinople in 1204 CE.

The decreasing power of the pope following the end of the Western Roman Empire in 476 CE conflicted with the rise of Byzantine power in
the East.

The Roman Catholic Church affirmed the idea of papal supremacy at the First Vatican Council in 1870 CE.

Answer 1

The best evidence that supports the historical claim that the East-West Schism did not begin in 1054 CE, but that the mutual excommunication was part of an already growing division is the Crusaders from Western Europe looting and sacking the city of Constantinople in 1204 CE. This event demonstrates a significant conflict between Western Europe and the Byzantine Empire, which suggests that the division and animosity between the two regions had been building up prior to the formal excommunication in 1054 CE.