Why is Islam especially widespread in northern and eastern Chad?

The prevalence of Islam in northern and eastern Chad is rooted in a long history of migration, trade, and the formation of powerful political states.

The region’s ethnographic history was shaped by the continual influx of nomadic, increasingly Arabicized populations entering from the north via Fezzan and Tibesti, as well as from the Nile valley via Darfur. These groups established sophisticated kingdoms, such as Kanem-Bornu, which gained prominence by controlling trans-Saharan trade routes.1234

The expansion of Islam was central to the development of these states, including the sultanates of Wadai and Bagirmi, which emerged in the 17th century through the process of conversion. Islam became well-established in major towns and among Arab populations, forging a sense of unity across diverse ethnic groups. Conversely, animism remained more prevalent in the southern regions, which were historically targeted by these northern Muslim states for slave raiding.345