Slavery was an important aspect of the Abbasid Caliphate. The Islamic outburst from the arabian Peninsul as not only north into the Levant and Middle East, but south into the western Indian ocean which became known as the Arabian Sea. This led to expanded trade with both India and East Africa. Trading posts were set up along the coast of East Africa. And slaves were an important component of that trade. It was the beginning of the Indian Ocean slave trade. This all began some two centuries before the Abassids took power, but continued throughout the five century history of the Abbasid Caliphate. Slaves were not, however, a major part of the work force as had been the case in the clasical society of Greece and Rome. This was the case for the same reason that slavery was not central to the economies of Mesopotamia and Egypt. The heart of the economy was the rural peasantry. Agriculture was the basis of almost all ancient societies and produced most of the society's wealth. And the peasantry had very limited rights or social status.
He led important campaigns and expanded his empire from Greece to Persia, Babylon, Egypt and beyond, taking advantage of local political contexts as he conquered new territory