Feudalism was a medieval system of government which came into existence in Europe in the tenth century. The conditions which prompted the development of feudalism are part of the reason why it was able to take root so efficiently. A wave of invasions of barbarians, including Vikings, in the ninth and tenth centuries created a genuine need for a system of government which could protect its citizens. Under feudalism, military service was provided to the lord in return for land, thus providing the security that Medieval Europe needed.
In addition, feudalism bound everyone in society to each other through a complex network based on loyalty and duty. From the king to the humble serf, entire societies were interconnected and dependent on each other, thereby creating a system which was so embedded in society that there was simply no alternative.