How did crusades impact on world history?

The Crusades had far-reaching political, economic, and social impacts, some of which have lasted into contemporary times. Because of internal conflicts among Christian kingdoms and political powers, some of the crusade expeditions were diverted from their original aim, such as the Fourth Crusade, which resulted in the sack of Christian Constantinople and the partition of the Byzantine Empire between Venice and the Crusaders. The Sixth Crusade was the first crusade to set sail without the official blessing of the Pope. The Seventh, Eighth and Ninth Crusades resulted in Mamluk and Hafsid victories, as the Ninth Crusade marked the end of the Crusades in the Middle East.