All spiritual practices maintain some form of connection to unseen worlds, be that Buddha fields or the heaven promised so prominently in Christianity and Islam. In some regard shamanism is not that different; however, where those religions offer the unseen world in an afterlife, shamanism opens those realms in this life as well. Plus, it’s a vastly more expansive, animated, and interactive version to the concept.
Shamanic practice has been described as crossing the veil, walking in other worlds, and a direct spiritual engagement with spirits, deities, and other realms. Naturally, such processes bring one into contact with unseen worlds, and the beings that populate these domains. It’s been going on since day one, since that first proto shaman took on the work.