Renaissance literally means rebirth. It was the period of intellectual changes that occurred at end of medieval and beginning of modern ages. The causes of renaissance are as follows:
Military expeditions in Europe at the end of the 11th century to 13th century to recover holy land from Muslims led to Christians coming in contact with enlightened people of east, long voyages, study of Geography etc.
Commercial Prosperity European businessmen on Business tours getting new ideas . European cities became centres of international trade with tourist. Enormous wealth with businessmen created desire in them to learn.
Capture of Constantipole in 1453 which was the capital of Eastern Roman empire and all routes from Europe to Countries of East, fell in their hands. Leading to discoveries of new trade routes and hence countries.
Mongolian state council was graced by cardinals of Pope, Budhhist monks of India, craftsmen of Paris, Italy, China, Mathematics and astrologer of India. East came in close contact with west.