KNITTING HISTORY 101 at link! "The oldest real knitting (formed on two sticks by pulling loops through loops) we've got is 'Coptic socks' from Egypt, from around the year 1000 CE. There are quite a few fragments, all of them done in shades of white and indigo, in stockinette. Many of them have Khufic (a decorative Arabic script) blessings knit into them, or symbols to ward off evil, or both." We assume knitting had been around a while before then, given the complexity of this work!
Knitted jacket from the 1500s. This connects to History 101, a history of knitting (on knitty.com), and shows examples mostly from the Victoria and Albert Museum. There's a link from Knitty to the Victoria & Albert where you can search for knitting.
Many women (and in some places, men) had to work every day - except perhaps the Sabbath. They didn't always have the luxury of sitting to knit. They knitted while walking to market, or fetching home fuel (like this woman, who's lugging peat), and at many other moments in their busy lives.