At first glance, nineteenth-century Brazil and the Ottoman Empire appear as two opposing and unrelated societies: one, a young, Christian state in the New World, and the other, a seven hundred year-old Muslim empire spanning across parts of Asia, Africa and Europe. There was however at least common element in both societies: African slavery. While the experiences of these slaves are in no way entirely congruent, within African slave communities in both Brazil and the Ottoman Empire, there existed female-dominated religious communities based largely on African spiritual beliefs. The most popular of these in Brazil was Candomblé, and in the Ottoman Empire, the Zar/Bori. Evidence suggests these practices played important roles in the spiritual beliefs, social organization and cohesion in their respective African communities. As a result of the relatively advanced state of slavery studies in Brazil, a great deal is known about Candomblé; For the Zar / Bori of the Ottoman Empire, however, much less is known, as scholars have only just begun to address its existence. Even a quick reading of the secondary studies suggests some exciting avenues for comparative research. In this paper, I argue that these two African-based religious practices are comparable and thus the Ottoman historian can draw upon the more advanced research from Brazilian studies to help formulate new research questions and approaches. The first task is thus to detail their similarities. Particular research questions include: What are the origins of these two religious practices? What was their role in the African communities? Who were the attendees? How did the members of the mainstream society view these practices? What was their societal function? What was their position vis-à-vis the state and how did they help to organize resistance against slavery? And most importantly, in what ways do these religious practices challenge contemporary class and gender structures? The implications of demonstrating the comparative nature of the Candomblé and Zar/Bori are twofold. First, it bridges the artificial boundary separating Atlantic and Middle Eastern slavery studies. Second it aims to advance the discussion on the common experiences of the global African Diaspora.