Every single great civilization in the history of mankind has started out simply enough, but the single most important driving factor of where civilizations spring up and why is water. Without it, man cannot exist. Water is the most important element to humanity. It shapes it and urges it forward, all the while nurturing and allowing communities to thrive.
Over the ages mankind has built great port cities that center around rivers, lakes, and oceans. Every single civilization that we know of today has sprung up around a body of water in one form or another.
The rivers and other bodies of water that mankind's first cities where built by not only provided drinking water and a means of irrigating crops, it also was the first way to quickly move from one area to another. In the time before paved road ways and cars, the fastest way to transport goods was via a main water system.
Vast armies took to the seas. Merchant princes brought exotic goods from half the world away. Without water, they never would have gotten their products back to their home countries within any reasonable amount of time. It would take years for someone to travel by foot or horseback from Italy to China. But with the ocean, the ships that went out to sea came back within the same year, if not sooner.
North America would never have been found and settled by the Europeans if men like Christopher Columbus hadn't taken the job to find a shorter passage to India. There would be no other way to get there but across the seas.
We judge the progress of a civilization by whether or not they have fresh clean running water and indoor plumbing. For the most part Third World countries do not have these modern conveniences. It is only when mankind has taken control of water and put it to use that it's civilization can thrive. The society is no longer focused on acquiring basic needs like food and water, and it can begin to thrive and create its own unique culture.
Water is the most important element in existence, for without it, we'd have no culture at all.