Without steam and electricity, slaves were the source of all power.
In the Middle East, around the time of the Crusades, the ones decreed by Popes, not by a Bush, many countries had slavery problems. Many people were being taken as slaves by neighbouring groups and a large amount of time was spent in making treaties with the countries on their borders.
One country had difficulty enforcing its treaties because of disobedient minor chieftains within its borders. This led to reciprocal slave-hunting invasions from the countries next door and the Sultan was fed up with the situation.
He called in his chief Ayatolla and instructed him to bring all slave hunting under centralised control. There was to be no more unauthorised kidnapping over the borders of countries with which there was a treaty.
After much discussion, coercion and an occasional beheading amongst his subordinate Imams, the Ayatolla was in a position to do just that. All slave kidnapping would be under the control of one Government appointee.
He was able to appoint an Imam for all seizings.