Answer:
An advancement in medicine and math.
Step-by-step explanation:
When Christians moved to the Middle East, they learned a lot about the new culture. The West and the East merged their food, culture and ethics for the first time. They learned about a number of new things that were otherwise unknown to them. Also, the economy and trade sectors of both countries flourished. New foods and clothing materials like muslin were now available in the Western markets. The Muslims also benefited in a similar way. They learned about arms and ammunition that were otherwise foreign to them. The concept of standing army was introduced to them. Also, it was a great opportunity for Muslims to show their unity. They also promoted schools and mosques heavily during that period of the history. Feudalism was a huge issue in Europe at that time which was solved due to the crusades. The Western Europe got free of the system of feudalism. Also, medical advancements were noted by Persian and Arabian soldiers. This improved the lifestyle of people living in these countries. The East and the West came together for the first time and gave us a glimpse of the Renaissance. A heightened knowledge of geography, literature and mathematics was passed. Cultures intermixed to increase the knowledge of humans and the pages of history were marked with a sense of certain enlightening knowledge.