Very true but not as well known as it should be. The woodland Indians of East Texas had a very valuable commodity, Salt. This was traded for things they did not have locally like knapping stone. I have a beautiful arrow point made of Black Obsidian that I found on our farm when I was a teenager. Far West Texas is the closest place where this volcanic glass occurs, about 800 miles from here with a lot of not much for half of the distance even today.