The war lasted for 500 years between the Crusaders (Christians) and Muslims. The reason for this war was to stop the Muslim in invading Europe and trying to win the Holy Land for Christendom. Crusades in the Middle East introduced to items and goods which were new to Europeans. Muslims introduced silk, spices, textiles, carpets also foods like sherbet, fruits, sugar, coffee, and rice.
When demand rises people want more of a product, but if the amount of that product (supply) is low it's more difficult to acquire said product, making it more expensive.
I think it's because they didn't want it to be so easy for someone to step in and issue new decrees randomly. Everyone would need to agree, given that America runs on a democracy.
