The Crusades were a catastrophe for Europe and mostly a nuisance for the late Byzantine Empire. The victory of the First Crusade was almost an accident and that was the only one that might be considered successful.

Meanwhile, the Moorish conquest of Southern Europe began in 711 AD and lasted until the Columbian Era - practically the year European Colonialism began.

And The Golden Horde dominated Eastern Europe for 200 years, starting in 1240, after wrecking their way into Poland and turning back when they ran out of anything worth conquering.

Hell, west Rome fell to other Europeans. Viking Age, Europeans.

Because all the action was in the Eastern Empire. The West was functionally abandoned by the time it fell.

And that was after centuries of humiliation, all the way up through what would become France, England, and Spain.