Why did the trade in african slaves increase dramatically in the seventh century?

This was the time when Islam started spreading through Africa and those who resisted it and fought wars against Islamic conquerors would be enslaved and sold. Europeans also started participating in this slave trade and would buy numerous slaves from the Arabs who would enslave their prisoners of war and who often traded with Europeans.

If he breaks the law then he had to resign from his post and so he'll lose his/her powers.