Which culture, empire or civilization studied so far made the greatest contribution to world history?

In my opinion, the Sumerians have made the greatest and most useful contribution to world history, specifically, the wheel. Although there is some question as to whether or not they actually invented it, most experts will agree that this society perfected it, for the wheel is not that useful unless coupled with an axle and socket. The wheel is arguably the most widely used, useful technological development in history. I bid you to count how many uses it has just inside your home.

The wheel has enabled countless tasks to be performed with greater ease. Ancient Sumerians used the wheel to develop trade and enable goods to be traded farther away from home using horse drawn carts. During times of war, wheels were affixed to chariots in which a person could ride and cover ground more quickly. This let the warrior slay more enemies in a shorter length of time and also provided some protection. There are burial sites dating back to 3700 B.C.E. that have been excavated and findings include people who were buried on carts and wagons. The concept of the wheel was probably also used in the building of the ziggurats through either transporting construction materials or helped with putting those materials in place.

There are countless examples of how the wheel has helped develop global societies today. The wheel is used in almost every facet imaginable. It has promoted and enabled trade by truck, train and plane. The wheel has given rise to construction, tourism, and agriculture, to name a few examples. It was instrumental in the settling of the west in our own country, moving people over large landmasses by wagon train. Even something as simple as keeping time on a wristwatch or the mobility of your vacuum cleaner can be credited to the wheel.

I think that there are MANY developments through history that have been important and imperative to the evolution of modern societies, including writing, but the wheel has allowed humans to go places and explore; to build structures and reap harvests with ease. Without the wheel, we might not have developed as we are today. I can speculate that we probably wouldn't have settled as much of the globe, the population might be smaller, structures would be more primitive, and the entire face of the planet would be different today if it weren't for the wheel.