My father use to do this when I was so you in the village but I never considered it so special stuff. But now that I know that natural leather products is good and economically rewarding I wish I pay attention then.
From some of what I learnt online. There are natural and chemical methods. I think will Peter the natural so I got this for you among the numerous ones. https://m.wikihow.com/Make-Leather-Naturally
Thanks!