* Medical knowledge: The Crusaders learned new medical techniques, such as the use of cautery and the amputation of limbs.
* Architectural ideas: The Crusaders were inspired by the architecture of the Byzantine Empire and the Holy Land, and they brought new architectural ideas back to Europe.
* Artistic ideas: The Crusaders were exposed to new forms of art, such as the use of mosaics and stained glass, and they brought these new ideas back to Europe.
* Philosophical ideas: The Crusaders came into contact with new philosophical ideas, such as the works of Aristotle and Plato, and they brought these ideas back to Europe.
* Religious ideas: The Crusaders brought back new religious ideas, such as the veneration of relics and the cult of the saints.
* Economic ideas: The Crusades led to increased trade between Europe and the East, and new economic ideas, such as the use of credit and the establishment of banks, were introduced in Europe.