The Sumerians were the first people to migrate to Mesopotamia, they created a great civilization. Beginning around 5,500 years ago, the Sumerians built cities along the rivers in Lower Mesopotamia, specialized, cooperated, and made many advances in technology. The wheel, plow, and writing (a system which we call cuneiform) are examples of their achievements.
1 In a Parliamentary System, the head of state is usually a different person than the head of government (not in every country). 2  The HOG is often vested with more official power, but holds that position for a relatively short time.
This is in contrast to a presidential system in a democracy, where the head of state often is also the head of government, and most importantly, the executive branch does not derive its democratic legitimacy from the legislature. parliamentary system may be a bicameral system with two chambers of parliament (or houses): an elected lower house, and an upper house or Senate which may be appointed or elected by a different mechanism from the lower house.