A mosque is a place of worship, the word mosque comes from the Arabic word masjid. A larger collective mosque is called a masjid jami. Larger mosques offer more services to their community.
Muhammed was the prophet and founder of Islam. Most of his early life was spent as a merchant. At age 40, he began to have revelations from Allah that became the basis for the Koran and the foundation of Islam. By 630 he had unified most of Arabia under a single religion.
A caravan often carried luxorious and lucrative goods, sush as silks or jewlery. They would trade these for salt, gold, copper, or slaves.