In the period following the fall of Rome until year 1400 there were three predominant areas of military power; Western Europe, Middle East, and the Asians. Their warfare differed because of values, motives, and styles. .
Western Europe valued chivalry. They believed in a code of honor or rules of war. They fought for religious purposes; for example the Crusades. The Crusade wanted to regain lost territory in the Holy Land. The Westerners were not as very mobile, they had heavy cavalry (Knights) who were more defense oriented. Their population in Europe was becoming more centralized around cites. Their style of warfare included armored phalanx, longbow, and conservative tactics. Western Europe also benefited from a healthy economy and advances in technology.
In contrast to the West, The Middle Eastern Arabs didn't value human life or a code of honor. They fought all those who were not share the same beliefs as them. They followed the Koran which explained their motives. The Arabs used a lot of Cavalry especially during the Crusades and would be considered very mobile because they could disperse their forces quickly. They fought to defend the holy land. Although cavalry was effective, in the end infantry will revival.
The Mongols in Asia did not believe in chivalry. Also they had very little value for human life and so the kamikaze was born. Kamikaze would give his own live for the sake of killing others. This was valued as an honorable death. Mongols were extremely mobile and used physiological warfare. They just fought to concur and had no religious motives. Genghis Khan was the greatest Mongol leader who united all the tribes buy fighting and getting them to join him and he took over all of Asia and got as far west as Hungry and Poland. The Mongols had heavy cavalry and some of the specific weapons used by the Mongol cavalry included the Lance used by the heavy cavalry and the Asian bow, Javelin, and Lasso used by the light cavalry.