This is a book about the history of Portuguese Jews in an overseas diaspora. In a sense it is a chapter of the historical narrative of Portuguese discoveries and expansion, and of the rivalry with other European countries. It certainly is part of the long history of Sephardic attempts to survive and adjust to adverse conditions, at a moment when they were compelled to seek a life of safety in lands distant from the Iberian Peninsula. But it is, as well, a chapter of the history of West Africa. Together with both Jewish and Christian Portuguese, African societies opened coastal and riverine paths to an Atlantic world in construction since the fifteenth century. In doing so they shared responsibility for the impact of their local and regional histories throughout a wider, even a global world. In many ways, African and Eurafrican agency made possible the complex intercultural relationships that constitute the subject of this book. As historians we seek answers to this apparently simple query: How was it possible for Portuguese to engage in trade and also to be Jews in an African setting?