The thunder cult is the clearest place to watch West African religion behave as a region rather than a set of separate systems. East of the Fon, among the Yoruba, Shango holds thunder and lightning, wields a double axe, is served with the same thunderstones, and imposes the same kind of claim on a struck house. Among the Ewe to the west, So occupies the same office. These are neighbouring peoples with centuries of trade, warfare, marriage and shared divination between them, and their thunder deities have influenced one another continuously.
The atlas records this as resemblance and shared regional pattern rather than as identity. Xevioso is not a Fon spelling of Shango and Shango is not a Yoruba Xevioso; they are distinct deities in distinct pantheons whose cults have been in conversation for as long as anyone can trace, and whose common features are evidence of that conversation.
The crossing to the Americas kept the pattern. Shango travelled with Yoruba captives and became a major figure of Cuban and Brazilian practice, and the double axe went with him. The Fon contribution to Haiti came through the Rada rite, where the thunder office is filled somewhat differently, and the neat one-to-one mapping that popular accounts like to draw between African deities and their diaspora counterparts breaks down exactly here. What crossed was not a pantheon chart. It was people, in specific ships, from specific ports, carrying what they knew.