Using historical linguistic methods in conjunction with archaeology and documentary sources, my research traces the intellectual and social history of slavery in the lower Congo between 500 B.C.E. and the nineteenth century. Scholars have long recognized that slavery in the region predated the arrival of Europeans in the fifteenth century, but they generally assume that it was a changeless institution prior to the transformations induced by external forces in central Africa. Instead, I seek to demonstrate that slavery emerged and changed in the lower Congo between 500 B.C.E and 1500 CE, and that these earlier transformations are crucial to understand how people in the region interacted with the emerging trans-Atlantic slave trade. My study opens up questions about how the logics of exclusion, violence and attribution of slave status during the Atlantic era have deeper roots in earlier endogenous processes, such as the advent of cereal farming, the introduction of iron and inter-group contacts. In order to investigate the period before the Atlantic Era, I propose to explore how and why Bantu-speaking individuals enslaved those deemed as vulnerable outsiders to promote new forms of power amidst contexts of material change. I also intend to understand the role of enslaved outsiders both in resisting masters' claims of domination and promoting cultural transformations. I further explore how these earlier experiences created a pool of concepts and practices around slavery that informed the logics of dispensability that provided slave ships with human beings during the Atlantic era. In its focus on slavery in a large span of time, my project engages with and builds on new paradigms within slavery studies, providing a detailed study of the construction and reconfiguration of this category in a specific region. In addition, my work will contribute to studies of Bantu expansions on Central Africa and the trans-Atlantic slave trade.