Until the early Middle Ages in Europe, all textiles were made from wool. Cotton was a luxury fibre which arrived from the East, people knew that it grew on a plant, but had never seen a cotton bush. So they concluded that cotton, like wool, came from a different strain of sheep which grew and lived on trees as the picture shows. The branches of these trees were flexible so that they could bend and allow the 'tree sheep' to graze grass from the ground. Hence the name 'tree wool'.
