I'm friends with hippies and I hear it every year, this year is no exception. Mushroom growing shamans going house to house with their reindeer, dropping off psychedelic gifts for the happy Siberians.
As awesome as that sounds, I heard it from hippies so of course my woo detector is going boop boop.
Hopefully somebody can come along and address this specific question.
But last year there was a thread on Pagan traditions in modern Christmas with a lot of useful answers about the origins of Christmas traditions in the anglosphere.
I’m not an historian, but I am an ethnobotanist (intersection of anthropology and biology) and involved in contemporary indigenous religious traditions from Siberia. So, as you might imagine I’ve heard and wondered about this often-repeated story.
To me most indicating is that there are no scholarly sources that support the connection between Santa Claus and Siberian shamans. Even the few scientists often cited in popular articles to support the claim, have written no articles discussing a possible link. Any possible Siberian origin for Santa is thus either unstudied or non-existent. Either way meaning that any conclusive statements confirming the connection are unscientific.
It is often claimed that the image of Santa originates with shamans who consume Amanita ritually. Popular articles usually talk about visually comparable aspects of (imagined) shamanic practices and contemporary Christmas traditions, which gives the impression to that the latter was derived from the former. There are two reasons to why this is unlikely: Shamanic traditions were likely to be different form those claimed in these articles; and There are more likely origins for modern Christmas traditions.
Most popular articles talking about a presumed Siberians shamanism – Christmas connection start by saying that many people think that Coca-Cola invented Santa and that this is not true. Indeed, Santa was not invented by Coca-Cola, however not being completely invented by a corporation does not mean that Santa has been inspired by shamanic practices.
Most contemporary Christmas traditions are more likely to originate in European cultures. (Like is outlined in the tread u/DuvalHeart linked) In Rome Saturnalia was celebrated. In Germanic cultures Yule was celebrated, where in some traditions Wodan (Odin) or other figures would bring gifts. As Christianity spread, these traditions were absorbed into local Christian traditions. During the Middle Ages children were often given gifts on the evening before the name day of Saint Nicholas, an early Christian bishop. Subsequently during the late Middle Ages (pre-Christian) local traditions and Saint Nicholas developed into various traditions, which would in turn inspire Santa. In the Netherlands, Saint Nicholas became known as Sinterklaas who is still celebrated as the predominant December-based gift-giver. In England the tradition of gift-giving moved to Christmas day, and their gift giver became known as Father Christmas.
By the 17th century many modern Christmas traditions were already present in some form in western European cultures. For example, the 17th century painting ‘Het Sint-Nicolaasfeest’ (‘The Feast of Saint Nicholas’) depicts people looking up into the chimney through which Saint Nicholas would have entered the home.
From the 19th century Ded Moroz, a figure from Slavic mythology, mixed with the Saint Nicholas tradition became the gift giver in Russia. A figure derived from Ded Moroz is present in indigenous Siberian peoples, known as Kish Babai (Old man Winter) in Tatar or Khys Khaan (Lord of Cold) in Sakha. At its earliest possible cultural exchange between Russians and indigenous Siberians surrounding this winter gift-giver started around the 19th century. Much too late to have inspired western European and American Christmas traditions.