I stumbled upon this article about soap and how long people have used it. Then one thing lead to another and I started investigating how soap was made. But almost all "recipes" that are "traditional" use lye as one component. Now lye has been available to purchase for a very long time, but this wasn't always the case and having looked into how lye is made it sounds a bit too advanced for just anyone to make. I can be wrong but it seems like that.
So what did they use to make soap without lye?
Typical, just after posting this I found out that one can easily make lye at home from ashes: http://www.wikihow.com/Make-Lye
Anyhow, I guess we didn't know about lye all the time and soap has been around for ages, so the question still stands :)
Bouncing Betty also known as soapwort. When the root is in water it releases a mucilaginous, soapy liquid that can help to remove grease and dirt