Slavery existed before in Africa societies that is to say, domestic slavery and internal slave trade, which provided a favourable situation for continuation of the lucrative slave trade.
The Abolition movement which had begun in Britain and her overseas territory first took effect in West Africa. The decline in west African trade encouraged the expansion of trade in East Africa especially with America and West Indies.
Slave trade was difficult to stop because of division of African tribes against each other .This meant that African tribes would find it difficult to unite together and resist the slave traders, who raided their societies using organised bands of men.
Disregard of human life ,many African rulers tended to put less value for the lives of their subjects whom they ruled for example quite often, a ruler of a tribe would easily order his warriors to attack the villages of his subjects and seize their property ,kill some of them .
Active participation and willing cooperation of African chiefs and coastal traders who were making a lot of profits made the slave trade last for so long.
Many European countries depended on the products of slave labour in West Indies and America for example, British industries depended on raw sugar, raw cotton and unprocessed minerals from America which she was not willing to loose.
European slave merchants and Africans involved in the trade were blinded by the huge profits made from the trade.
There was smuggling of slaves outside the forbidden areas. Slave traders would pretend to sail northwards when sighted by British patrol ships but would change course after British navy ships had disappeared.
Other European countries refused to co-operate with Britain to end slave trade because they had not yet become industrialized, and therefore they still benefited from it for example Portugal and Spain.
The only economic alternative of slave trade was Agriculture which was not reliable compared to the booming slave trade.
The anti slavery campaign was too expensive for Britain alone to compensate slave owners.
Stopping slave trade in the interior was difficult because Arabs were in control of large areas.
The East African coastline was long which delayed the anti-slavery group penetration in the interior.
Due to the tropical climate, most British personnel were affected by malaria which hindered the stopping of Slave trade.
Seyyid Said and Bargash were always unwilling to end slave trade at once due to fear of losing revenue and risk of rebellion by Arabs who found it profitable.
The anti-slavery group was small compared to the East African Coast.
European powers continued with slave trade, they shipped the slaves cargos in to ships bearing American Flags.