Prior to the Neolithic Revolution humans were nomadic hunter gathers. We moved around in search of food and often times followed animals. After the Neolithic Revolution humanity gained a green thumb so to speak and began to harvest plants and domesticate animals to survive. This allowed humans to specialize in certain trades as we had more time to do things and spent less time worrying about where our next meal is going to come from.
<span> The middle ages was the rise of ethnocentrism, which evolved later into modern civic nationalism in most of Europe, the ascent of the great Italian city- states, and the rise and fall of the Muslim civilization</span>