The correct answer is - It was a site of manufacturing and production.
The Swahili Coast has a long history as a trade center in the western coast of the Indian Ocean. It has an excellent position because it is where traders from Asia and Europe were passing and trading goods, so it became a very important stop and trade center. The place itself had a lot to offer, and the list of the products that were exported from here is very long, with some of the most important being the gold, copper, coconut oil, slaves, concubines, glass, cottons, spices etc.