What is Shamanism... and why is it relevant to us now?

As more and more of us are becoming interested in Shamanism, I find myself having conversations with people trying to demystify it. Some express concerns about it being 'weird' or 'tribal'; others regard Western Shamanic practitioners as hopelessly deluded romantics seeking inspiration in outdated animism; while others think that only indigenous peoples may practice it. Shamanism is said to date back 30,000 years, making it the oldest spiritual source that we know about. There is archaeological evidence of it all around the world and while there are cultural variations according to the land in which it has developed it is also fair to say that a common theme weaving through is 'Indigenous N