
While the word lacks a universal definition, it implies that power was held by local landowners (usually nobles or clergy) and gave some legal privileges, combined with the duty to serve the monarch. The dominant political and economic system in medieval Europe is known as feudalism. The Mongol Empire reached eastern Europe in the 13th century, opening the Silk Road for European travellers such as Marco Polo. The crusades united Catholic kingdoms in wars to conquer the Holy Land and other non-Catholic realms. The High Middle Ages from the 11th to the 13th century was a period of urbanization, with foundation of castles, cathedrals, universities and merchant companies such as the Hanseatic League. European kingdoms were founded in this period by peoples such as the Franks. The Early Middle Ages from the 5th to the 10th century was a time when political and economic power were largely decentralized. Similarly the Renaissance, commonly held to be the transition from medieval to modern times began perhaps as much as a century earlier in Italy than north of the Alps. Some historians also argue that it was the rise of Islam, not the fall of the Roman Empire that caused the biggest shift in the Mediterranean world. The periodization varies between parts of Europe in the Nordic countries the Middle Ages are held to have begun around AD 1000 with the establishment of Christianity and the decline of Viking raids. During this long period of time many empires and societies emerged, flourished and disappeared. The Middle Ages saw the spread of Christianity to every part of Europe, the Islamic Golden Age with the Caliphates expanding to the Iberian and Balkan peninsulas and the subsequent Christian crusades to the Holy Land as well as the Mongolian invasion from the east and the Black Death killing a substantial part of the European population.

The Migration Period from the 4th to the 6th century marked the end of the Western Roman Empire (while the east survived as the Byzantine Empire) and the expansion of Germanic tribes across western and southern Europe. The Mediterranean region during the 7th century
