Royal vassals : Old African Christians in the Atlantic world

In the sixteenth century, hundreds (if not thousands) of free blacks, some of them first generation Africans (manumitted slaves) acquired royal permits to embark in fleets to cross the ocean as vassals of the Castilian crown, that is, as Old Christians. Free bozales (recently arrived from Africa as slaves) and their descendants, ladinos (hispanized Iberian-born Africans), successfully argued in the House of the Trade in Seville that they should be given permission to travel to the New World because they were Old Christians from West Africa. While such applicants may be considered as hispanicised (ladinos) as they were fluent in Castilian and were well known in the Iberian cities where they lived, ultimately it was the colour of their skin and African heritage that enabled them to successfully argue that they were as Old a Christian as any white Iberian and that they should be given permission to travel to the New World. In my paper I explore this puzzle: how did free Sub-Saharan Africans manage to successfully claim an Old Christian status and travel in the Iberian Atlantic?