In 1233, Genghis Khan, with a massive force of highly skilled Mongol warriors behind him, attacked Russia. By this time, the Mongols had invaded and conquered various parts of China and the Middle East, and Moscow found itself hard-pressed to withstand the ruthlessly targeted invasion of its territory, as Genghis Khan gained control of more and more swathes of Russian land. With the final fall of Russia to Mongol forces in 1240, the country came under firm Mongol control and would remain a part of the Mongol Empire for almost three centuries (until Ivan the Great’s liberation of his people in 1480). As a Mongol-controlled state, Russia adopted a curious mixture of Christian, Mongol, and Islamic practices, although the Russian people were allowed to preserve a great deal of their religious and political policies. The Mongols moved the center of Russian political, social, economic, and cultural primacy from Moscow to Kiev; the city would remain a potent force within Russian life for centuries to come.

Prior to the invention of the cannon in the fourteenth century, the most useful weapon a lord or a king could have was a castle. Castles were built of stone and could withstand constant barrage from trebuchets and catapults provided they were sufficiently manned; however, the invention and subsequent improvement of the cannon gradually rendered castles obsolete as the additional firepower of a cannon could blast right through the stone walls of a castle. This changed not only military life, but also social, economic, and political life in Europe as the feudal system, predicated in many ways on the protection offered by the lord's castle or stronghold, became gradually obsolete.

The Battle of Talas was fought between the Arab Abbasid Caliphate and the Chinese Tang Dynasty in 751 CE. Prior to the battle, Chinese forces had been spreading rapidly westward and facing little opposition; however, at the Battle of Talas, they were defeated by the Arab forces, and Chinese expansion was halted for several centuries. The battle is considered important for transferring control over the “Silk Road” from Chinese to Arab hands and for turning back the massive forces of the Tang Dynasty. Also, it is sometimes said that Arabs learned the art of paper making from the Chinese prisoners they captured in the battle, thus spreading paper-making technology to the Middle East and eventually Europe.

In 1096 C.E., Pope Urban launched the First Crusade in order to take back control of Jerusalem from the Seljuk Turks. The many crusades that followed all professed a desire for Christian control of the Holy Land, a place that both Christians and Muslims saw as an essential part of their religious identity. Although a Latin Empire was established in Constantinople during the Fourth Crusade, this development ultimately distracted from the crusaders' goals and deepened the schism between the two Christian churches. While the most positive result of the Crusades was arguably the European rediscovery of ancient ideas, this development was also unintended.

Temujin is the given name of the warrior ruler Genghis Khan. Genghis Khan united the Mongol tribes in the twelfth century under his rule and soon led his horde on a series of conquests across Eurasia. In the generations immediately following his death the Mongols conquered the largest land empire ever seen in human history - stretching from China all the way to the gates of Vienna, and including much of northern India and the Middle East. 

Pope Urban II was Pope from 1088 to 1099. He is most frequently remembered for initiating the First Crusade, which led to the temporary conquest of Jerusalem by the forces of Christendom and led to centuries of conflict between Christian Europe and the Islamic world.

The Battle of Tours was fought in modern-day France in the eighth century between the forces of Christian Europe, led by Charles Martel, King of the Franks and the forces of Islam. Since its formation a century earlier, Islam had spread rapidly throughout the Middle East and North Africa. By the early eighth century much of the Iberian peninsula was under Arab control and it seemed as if soon all of Western Europe would succumb to the Islamic invasion. Victory at the Battle of Tours stopped the tide of Arab conquest and preserved the rule of Christendom in Western Europe.

William the Conqueror was a Duke of Normandy when he invaded England in 1066. He defeated the recently crowned British King Harold at the Battle of Hastings, and in so doing took control of the Kingdom of England. This period of time is known in English history as the Norman conquest. It had dramatic consequences in English history, including the adoption of European style feudalism in Britain.

The Hundred Years’ War, with its forty-four nonconsecutive years of actual combat, finally came to an end in 1453, with a decisive French victory. France’s military position had been strengthened with a newly-formed alliance with Burgundy, allowing the French forces to concentrate all their military might on ousting the English. Eventually, the English army could hold on no longer, and with the declaration of French victory, England was forced to relinquish nearly all the French territory that it had once held under King Edward III. Only the coastal region of Calais was left under English control. Due to the overwhelming expenses run up by the war, both England and France raised taxes upon their respective populations, with the greatest burden falling, once again, upon the already struggling peasant class. The French king took special advantage of these circumstances and moved to shore up the monarchy’s position of dominance over the nobility, so that the French crown exercised more and more political, social, and even economic control.

Mahmud of Ghazni ruled over an empire in modern-day Afghanistan in the eleventh century. His empire grew immensely wealthy from the riches his armies plundered from northern India. He conquered or weakened many northern India states and paved the way for the Islamic conquest of India a few centuries later.