The Late Middle Ages was a time of positive change as well as disaster and upheaval. Trade developed across Europe as a result of the Crusades. After people went on the Crusades they were exposed to a variety of goods from a variety of different places that they had never seen before. Remember that on the manor they only had what they were able to produce themselves, very little was brought in from anywhere else. The Crusades created a demand in Europe for the kinds of goods that were being produced in other places such as fabrics (silk, taffeta, satin), spices, minerals, timber, wool, grain, fish, wine and olive oil. As a result, people began to leave the manors and live in towns where they could do other things besides farming. Many chose to develop trades and began making and trading goods at markets and fairs. These could only be held at certain times of the year (usually fall when the harvest was gathered) and people needed access to goods throughout the year, so people created shops in towns where they could sell their goods all year long. To protect themselves they needed to create walls around their shops and towns so people didn't come and steal their goods.