The first pictures you may come across when Googling images of the contents of medicine bags may be New Age crystals and little satin baggies of herbs (and crystals). I am not judging.
A closer look at a more historical (and possibly stolen) medicine bag (as for years 'archaeologists' just robbed grave sites, which is wrong if your descendents are still living) shows a bag with small bags of healing herbs, salves, and tools. This bag shown here is Tibetan. It contained 50 items, small bags of herbs and tools. Note the deer horn. It was useful for drinking the prepared medicines.
This sounds like the perfect bug out bag for the experienced nature walker. For someone who is at home in their environment hunting and gathering food a medicine bag, a good knife, a hunting weapon and the knowledge of all the ancestors is all that he needs. I want more. But, broken down to only what you can carry, special attention to the medicine bag is essential.
The best material for a medicine bg worn around the neck is elk skin. It will age to a nice dark tan as your sweat stains the outside. (just the outside) The contents will be dry and clean inside. Also there are bags made to wear around the neck. Passport pouches for the traveler are potential personal medicine bags.
If you are separated from your bug out bag, your med kit or other supplies, you will still be ahead of the pack with a good knife, a hunting weapon and a medicine bag.