It was buffalo hide, and they tanned it by scraping it with sharpened boned or antlers to get the extra flesh off, then soaked it in ashes, water, and it's own brain. They then strung it to stretch it and dry it. To hold the hides together they used the sinew (tough tendons, almost impossible to rip). My husband has tanned buffalo hides himself, and even with chemicals instead, it was a hard process and time consuming. But it goes to show you there was no waste. Also, almost every animal, has enough brains in it's skull to tan it's own hide. One example is the human male(ha ha jk). I forgot the few animals though, but none were used by Native Americans for hides. Almost forgot, the sinew was dipped in bees wax for added strength.