The roots of shamanism are lost in antiquity. However we do know,that given the similarities between shamanistic practices in the new world and Europe, that the fundamental elements of shamanism had been established as the first Paleo-Americans began to move across the Bering land bridge which connected Siberia to Alaska. This bridge disappeared about 12,000 years ago, as the Artic glaciers melted.
Another source of the origins of shamanic practice lies in the study of psychotropic plants. The ethnobiologist R.G. Wasson proposed that all major world religions grew from psychotropic experiences, and most shamanic cultures have some form of psychotropic plant associated with them. Siberian shamans make use of Amanita Muscaria, which has been tentatively identified as the divine Soma of the Rig-Vedas.
There are at least 80 different types of psychotropic plants the were, and continue to be used in North and South America, and American Indian shamans have made extensive use of both the red Mescal bean and peyote. An American researcher, R.K. Seigal, has also demonstrated a link between the psychotropic-induced visions of shamans and tribal pottery and weaving designs.
Of course drugs are not the only means of inducing ecstasy, and many shamanic techniques revolve around drumming, dancing, singing, fasting, sleeplessness, and physical feats of endurance.