What cultural exchanges took place?

spread and reform of existing religions and created syncretic belief systems and practices

Explanation:

During that period of time, technology in sea travel started to developed. This allow many people across the world start to sell their goods to people in anther country.

When traders visit another country, selling their goods is not the only thing they do. Sometimes they also socialize with the locals and learn several things about their knowledge, culture, and religion.

When they brought these things back to their country of origins, cultural exchange occurs and reform of existing religions / knowledge that people held in that country.