Although the crusades left relationships among christians, jews, and muslims strained one less destructive effect was the expansion of

Although the crusades left relationships among Christians, Jews, and Muslims strained one less destructive effect was the expansion of trade into Mediterranean and Middle Eastern countries.

Explanation:

Crusades were Holy wars taken by the military expeditions of Europe in order to capture the Holy Land Jerusalem from the invasions of Muslims. Due to such military annexations the relationship of Christians and Muslims suffered a lot. But crusades had a positive effect and it paved way fro the increase in trade with east and Mediterranean areas. Arabic numerals were replaced by Roman ones and silk, fruits, perfumes and oils were traded.  

It also increased economic growth, banking operations came into existence and new taxation systems were introduced. Islamic science, philosophy and medicine deeply influenced the west due to crusades. The relationship between Christians and Muslims grew bitter.  

this isn't a question and if you're going to list things be kind and use commas.