Post-Carolingian Europe was plunged into a period of disorder and violence that lasted until at least 1100 CE. Even though the specific invaders mentioned below had settled down by about 1000 CE, the overall state of lawlessness and violence lasted for centuries. In addition to attacks by groups like the Vikings, the major political problem of the Middle Ages was that the whole feudal system was one based on violence: lesser lords often had no livelihood outside of war, and they pressured their own lords to initiate raids on nearby lands. "Knights" were often little better than thugs who had the distinction of a minor noble title and the ability to afford weapons and armor. Likewise, one of the legacies of feudal law was the importance placed on honor and retribution; any insult or slight could initiate reprisals or even plunge a whole kingdom into civil war.
Meanwhile, a series of invasions began in the post-Carolingian era. Arab invaders called Saracens attacked southern European lands, even conquering Sicily in the ninth century, while a new group of steppe raiders, the Magyars, swept across Europe in the tenth century, eventually seizing land and settling in present-day Hungary. In Northern Europe, the most significant invaders of the period, however, were the Vikings.