Shamanism is very widespread across human cultures, but has a distinct strong historical tradition sourcing from the Mongol areas from Siberia south. These traditions are very old, and run back into the paleolithic, having a roughly contempraneous emergence with the earliest fertility goddess figurines, and representing the skills of the hunt as seen in caves such as Lascaux. The correspondence between shaman and the ascetic in Sanscrit illustrates the deep relationship also between shamanism and Eastern mysticism. However the world over, in ethic tribal societies, shamanistic practices have been commonplace. Intrinsic to Shamanistic practice is the idea of an interaction with nature spirits in ways which can heal, cause other people to become ill or protect the user in battle.
Some shamanistic practices involve the use of a power animal or a second soul.
For example in Aztec cosmology one has a birth soul called the tonal which represents the persona, and your astrological destiny. To really become a person of pwer, one also has to adopt or become possessed by a second etherial soul, manifested as a power animal ally called the nagual. By relating to the naugal very surprising things may happen. The tonal represents the ordered, bright clear aspect to existence and the nagual the dark, chaotic uncertain, undefinable aspect. This in no way equates with good and evil.