Nuclear arms race was a key factor in extending the time period of the cold war. The seeds of the hostility between USSR in US began after the end of World War I with the rising of communism in USSR in Stalin rule made it worse.
Governments typically had been either unitary or confederated. Or another way to say that is that they either focused on centralized power (in someone like a king) or particularized power -- the power in the parts of a kingdom rather than at the center.
So, for instance, in France (prior to its Revolution), all the power in the kingdom centered in the hands of the king. For 175 years, they didn't even have a meeting of the Estates General which was their version of a representative body. And the power of nobles on their lands was reduced while the king's power grew.
Meanwhile, in the German territories, there was a loose confederation called the Holy Roman Empire. One of the kings or princes held the title of "emperor," but he really had no imperial power. The confederated German states retained control over their own kingdoms or territories.
The American experiment mixed something of the best of both approaches. There would be strong central power in the federal government, but putting checks and balances on that power by retaining certain aspects of control in the hands of the states within the union.
Answer: Some scholars, such as Jared Diamond, believe that while the Spanish conquest was undoubtedly the proximate cause of the collapse of the Inca Empire, it may very well have been past its peak and already in the process of decline. In 1528, Emperor Huayna Capac ruled the Inca Empire.
