The Sumerian civilization was established in the valley of the rivers Tigris and Euphrates. This is the civilization that is considered to be the first one in the world, and the one that contributed to the rise of the other civilizations in the region. It was a civilization that was united under one ruler though, but instead it was designed in the manner of city-states. Each city-state had its own ruler and governing body which was functioning independently from the other city states, so Sumer was actually decentralized. The fact that each city-state had its own ruler was not an obstacle at all, as all of the Sumerian city-states were in good relations, constant contact, and they collaborated and supported each other. It might have even worked for the better that there was not a single ruler, as the power was never in the hands of only one person, thus a tyranny was avoided.
It was "Jan van Eyck" who was a northern European Renaissance artist who was one of the first to paint on wood panels with oil paint, although it should be noted that he was not the only one doing so at the time.
