Why did merchants, monarchs, and educators embrace islam?

The merchants embraced Islam, because it gave them a very important point of union with the clients and partners who had this religion, facilitating trade in Muslim towns. The monarchs, by belonging to Islam, in the same way as merchants, took advantage of religion to lay the foundations of alliances; and also because Islam taught them how they should be, and how to behave. The educators embraced Islam because the Muslims were in favor of education, they supported it and that favored the support of schools and teaching (including the study of Islam).

The answer is ethnic groups.