Medieval means "Middle Ages", and refers to the period of time from the 10th century to the 14th century. In this period the dealth rate increased as plague and illness struck the population. The Medieval time period is known for their music. During the middle ages a holy war called the Crusades was fought between the Christians and Muslisms. Europe sees many different changes as William the conquer introduced fuedalism into England. The signing of the Magna Carta by King John changed the power of the king by providing a system of checks and balances.