The period between the fall of the Roman Empire (sixth century, roughly) and the year 1095, is referred to as the Dark Ages. In western Europe, all political, social, economic and military organizations were fragmented simply because they had not yet began to develop. The idea of ‘The nation state’ in Europe was not even born. At this time, Germany, France, Spain and Italy were divided into several kingdoms, ruled by war lords who weren’t tightly loyal to their king. These landholding warrior lords were constantly seeking more power, land and wealth. For this reason, they waged war against each other.
The kings, on the other hand, controlled only the land within the boundaries of their kingdoms, which, often, didn’t yield enough wealth to enable them to build and maintain a large, standing army. Most of their resources were spent on defending their kingdoms, and the people living within them, from rapacious war lords.
The Christians south of the Pyrenees mountains were faced with another ordeal. Before the second half of the eighth century, all of Spain, save one small strip of land in the North, fell to the Muslims. It wouldn’t be for another three centuries until the Spanish Christians would begin the reconquest of their territory.
This begs one to ask; how could the situation in Spain be so acutely different from the rest of Europe? How was it that Muslims dominated Spain, a territory thousands of miles away from their homeland in the near East?
The answer to these questions can be found within the fabric of Islam.
Asbridge, Thomas. The Crusades: The Authoritative History of The War For The Holy Land. Ecco; New York, 2011.