By the early seventeenth century, slaves had become Comoros' most important export commodity, although the market for the islands' other products also continued to expand, mainly in response to the growing European presence in the region. To meet this increased demand, the sultans began using slave labor themselves, following common practice along the East African coast.

Beginning in 1785, the Sakalava of the west coast of Madagascar began slaving raids on Comoros. They captured thousands of inhabitants and carried them off in outrigger canoes to be sold in French-occupied Madagascar, Mauritius, or Reunion to work on the sugar plantations, many of which French investors owned. The island of Mahoré, closest of the group to Madagascar, was virtually depopulated. Comoran pleas for aid from the French and the other European powers went unanswered, and the raids ceased only after the Sakalava kingdoms were conquered by the Merina of Madagascar's central highlands. After the Merina conquest, groups of Sakalava and Betsimisaraka peoples left Madagascar and settled on Mahoré and Mwali.

Prosperity was restored as Comoran traders again became involved in transporting slaves from the East African coast to Reunion and Madagascar. Dhows carrying slaves brought in huge profits for their investors. On Comoros, it was estimated in 1865 that as much as 40 percent of the population consisted of slaves. For the elite, owning a large number of slaves to perform fieldwork and household service was a mark of status. On the eve of the French occupation, Comoran society consisted of three classes: the elite of the Shirazi sultans and their families, a middle class of free persons or commoners, and a slave class consisting of those who had been brought from the African coast or their descendants.

Data as of August 1994