Before the Islamic conquest, the Persians had been mainly Zoroastrian; however, there were also large and thriving Christian and Jewish communities, especially in the territories of at that time northwestern, western, and southern Iran, mainly Caucasian Albania, Asōristān, Persian Armenia, and Caucasian Iberia. There was a slow but steady movement of the population toward Islam. When Islam was introduced to Iranians, the nobility and city-dwellers were the first to convert, Islam spread more slowly among the peasantry and the dehqans, or landed gentry.