Answer:
Knowledge
Western Europeans incorporated Muslim ideas on maths, science, medicine and astronomy into their own thinking and practises.
The first hospital in Paris was founded by Louis IX after he came back from Crusade in 1260.
Culture
Many Western musical instruments were copied from instruments that originated in Islamic societies, including the lute, the guitar and the violin. It is said that Spanish flamenco dancing was influenced by the rhythms of Arab music.
Astrolabe
Astrolabe in Doha Museum of Islamic Art, Qatar
Trade
European noblemen bought goods that Muslim’s traded in – silk, spices etc – as the height of fashion. Western sailors adopted devices that had been refined by Arabs, eg the astrolabe, which aided navigation, and the triangular sail, which increased manoeuvrability. Without these Columbus would never have reached America.
Architecture
The pointed arch from Muslim mosques was copied in western Gothic architecture. Western castle-designers adopted the idea of concentric castles, with layers of walls, from Muslim castles they had seen on Crusade.
War and conquest
Large areas of Europe were conquered by Muslims. When these areas such as southern Spain were recaptured and placed under Christian rule Muslim customs and architecture remained.
Christians were encouraged to go on Crusade to recapture Jerusalem from the Muslims. Christians brought back ideas about knowledge and culture to Europe after their travels.
One historian writes that the fall of Constantinople and the end of the Byzantine Empire in 1453 sent a stream of refugees and tremors of fear, shock and despair throughout Christendom. Some historians believe that 1453 marks the end of the Middle Ages.
