Woad was used in ancient Egypt and had been discovered on mummy cloth. The Jewish people have long searched for the biblical blue which was lost over 1,500 years ago. It is called the Tekhelet. Many thought it was from the Murex snail. I believe tekhelet was made from woad. It passes all biblical and talmudic tests. To read more about this just google- What is the True Tekhelet? by Dr. Curtis Ward.