The postclassical period in western Europe is the period that began immediately after the end of the Roman Empire (the classical period) and is most often called the Middle Ages or the Medieval Ages. Some scholars prefer to use Medieval Ages instead of the Middle Ages because they believe this makes the time period sound trivial and inconsequential when compared with the classical period and Renaissance period.
The Middle Ages ended when the western Renaissance began. During the Middle Ages, the Catholic Church was the most powerful unifying force in Europe. Once Rome had fallen, there was not a government or country that had enough power to unify the continent.
The Church managed to accomplish just that and the royal kings, queens and state leaders were given most of their power from the Church through strategic allegiances. This was also the period when the Crusades began under Pope Urban.
The art and architecture during this period was also unique and emerged in a style called gothic. The English Canterbury Cathedral and the French Abbey Church of Saint-Denis were built using this gothic style.
The term postclassical is also used to indicate the period after the classical period to just before the "modern" period in subjects such as languages and literature. When the term is used in these areas, it tends to include a much larger period of time than when one is speaking specifically about the postclassical historical period in western Europe.