According to the description supplied by The Secret History of the Mongols, Black Shamanism is the only one of the many varieties that has preserved the main religious ideas and customs of Shamanism to the present day. Since the eighteenth century varieties of Mongolian Black Shamanism such as Darhad, Uighur and Urianhay have been subjected to academic scrutiny. Some of these groups, having not adopted the world-view of Buddhism, preserved their own beliefs and rituals until the end of the nineteenth century. As a result these were considered as the most dangerous sects. Mongolian history witnesses the many precautions that were taken by the authorities in order to keep such people, their regions, and ideas separate from others. Any suspicious activities and customs were immediately banned. Shaman religions appear to have evolved from as original religion that was established in an early stage of human development before the creation of nations, states, of literacy. The nature of Shamanism's decline, caused mainly by the influx of traditions, customs and ideas from neighboring nations and peoples is explored in detail. Likewise, the emergence of many varieties of Shamanism, such as Horchin, Barga, Buriad, Halha, Hamnigan, Horgoyd, Darhad and Urianhay, is also considered.