Below are a couple of articles discussing the interesting connections between Christmas myths, symbols and traditions, and Siberian Shamanism.
The Siberian Shamanism Origins of Santa Claus: Reindeer, Pine Trees, and.. Mushrooms?
http://www.shamanswell.org/shaman/siberian-shamanism-origins-santa-claus-reindeer-pine-trees-and-mushrooms
Magic Mushrooms May Explain Santa & His 'Flying' Reindeer
http://www.livescience.com/25731-magic-mushrooms-santa-claus.html
The Siberian Shamanism Origins of Santa Claus: Reindeer, Pine Trees, and.. Mushrooms?
http://www.shamanswell.org/shaman/siberian-shamanism-origins-santa-claus-reindeer-pine-trees-and-mushrooms
Magic Mushrooms May Explain Santa & His 'Flying' Reindeer
http://www.livescience.com/25731-magic-mushrooms-santa-claus.html