For more than two thousand years, Rome was a large, powerful, and dominant empire. The ancient kingdom seemed unstoppable, but within a few centuries Roman power fell and was annihilated. No one knows exactly how the end of the empire came about and it is still debated today, but there are some important recognized factors that caused the fall of Rome. The land of the barbarians lay beyond Rome's western border along the Rhine and Danube rivers and would slowly become a serious threat to Rome and ultimately lead to the fall of the empire. At first they posed no danger as they were just nomadic German farmers due to their poor agricultural skills. Even the barbarians could not develop a political structure, so they were small and weak compared to Rome. Indeed, Rome gained the loyalty of the tribes by using money, trade, and military honors and by turning them against each other. In the third century, however, the barbarians changed and became more complex, as garrisons and merchants stimulated the economic and sociopolitical growth of the border tribes. Farmers were introduced to Roman agricultural techniques that stabilized their population, and the tribes increased in size, leading to the founding of cities. As the population grew, the tribes created a more organized and complicated political constitution. The barbarians soon had stronger and larger armies and posed a threat of border raiding and mass migration to Rome. Another important factor that caused the fall of Rome was the recurring civil wars between emperors and usurpers, who are rebels who try to illegally seize power, such as generals or other officials. These frequent civil wars led to thousands of deaths, haphazard training... half of paper... and barbarians. While all this chaos occurred in the western part of the empire, the eastern empire functioned well and was still considered dominant by the rest of the world. They were protected from attacks because they had the Bosphorus Strait which gave the Romans an advantage as it forced the barbarians to fight on the sea which was not their strong point. They also had mountains that made it difficult for tribes to pass, and the mountain tribes already living there negotiated with the eastern empire and agreed to defend them. The army allowed a limited number of barbarians, which also prevented mass migration of tribes. The people also had a national identity and considered themselves Romans, so they easily protected the country. However, even though the Western Empire went up in flames, they did not fall easily and fought well before passing.