During the Middle Ages, cities where not very common. Cities where very hard to build, there needed to be a certain small town to be rich enough to expand. But, the big cities where developed by a leader, King or Queen. This leader had a large amount of money and would continually buy land and expand there territories. For a town to be successful they would need to be in a stable relationship with the big cities. The town folk would work the land in exchange for protection. But the town folk would also get unfairly taxed.