when i do not have access to what i need in my environment, get my earth pigments from cedar mountain drum works in portland oregon.
there is also a place online called earth pigments, tho i have never ordered from them, they have a huge selection of colors.
one of the best books i have ever read regarding earth pigments is called earth pigments and paint of the california indians by paul douglas campbell.
if you are really into earth pigments, this book is a must have.
i typically mix pigments with hide glue, but just like sinewing a bow, it must be kept warm while using.
you can use egg whites and i also have a small jar of acrylic medium that i use sometimes tho it is not "primitive"
you cannot use water as the pigments will just dry and turn back to dust.
i have painted bows and then sealed with various mediums.
but i would suggest ya try yr pigments on a sample piece of whatever material you are painting then using yr sealer to see how they work together before applying to yr actual piece.
if you do a google search, you will find a great deal of info on red ochre, the history, how it was used, how it was protected, and the sacredness of earth pigments, esp red ochre to many nna peoples.