However , slavery never became a significant part of the domestic economies except in Sultanate of Zanzibar where plantations and agricultural slavery were maintained .
The Southeast African trade reached its height in the early decades of the 1800s with up to 30,000 slaves sold per year .
Slavery never became a significant part of the domestic economies except in Sultanate of Zanzibar where plantations and agricultural slavery were maintained .
The Southeast African trade reached its height in the early decades of the 1800s with up to 30,000 slaves sold per year .