Under The Qajars
Due to several factors, the trade of enslaved East African peoples increased during the Qajar dynasty. Eventually most of the people sold in Persia as slaves were from the south eastern coast of Africa and the Horn of Africa. Until the mid-19th century, most enslaved peoples were transported by sea to port cities along the Persian Gulf, such as Bandar-e Abbas and Bushehr. From there they were forced to cities in the interior, where they were sold in public markets. The largest slave markets were in Shiraz and Isfahan, but enslaved peoples were also sold in Tehran, Tabriz, and Mashhad.
In the south, the enslaved often found themselves in the hands of Arab or European plantation owners. They were forced to work as agricultural laborers, and were subject to their holder's abuse without legal avenues of recourse. In the north they were held by the elite, who forced them to work as domestic servants, or merchants, who forced them to work in their stores.
In the middle of the 19th century, Britain began to pursue an aggressive policy of abolition of the Indian Ocean slave trade. As a result fewer enslaved peoples were transported by sea. This also affected which populations were targeted by slavers. The Indian Ocean slave trade had flourished because of monsoon winds that made the trip from southern Asia to eastern Africa relatively quick and easy. It wasn't as profitable to transport large groups of enslaved people over significant distances when travelling on land. For this reason the slave trade was reduced in Persia, but it did not disappear.
Read more about this topic: Slavery In Iran