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 presidential system, the legislature and the executive do not have to be aligned and often work against each other. 2  Policy implementation can be much slower and more moderated, at least in the US system.
In a Parliamentary system the legislative and the executive department of the government are very closely related and are interdependent for the performance of governmental functions.he Cabinet or the Council of Ministers enjoys the real powers. The Prime Minister is the real head of government. All the ministers are also all members of the parliament and are responsible to it for their acts and policies.