Egypt. Sumeria. The Indus Valley. Shang Dynasty China. The Olmecs. These are the oldest civilizations in each of their areas of the world, pioneers in the creation of states and tutors to the civilizations that arose later. Not coincidentally, each of them emerged in important river valleys: the Nile, the Tigris and Euphrates, the Indus and Saraswati, the Yellow River (or Huang Ho), and the Coatzacoalcos and San Juan. In fact, of the earliest civilizations, the only one that did not arise in a river valley was that of the Minoans on Crete. Clearly, river valleys had a powerful effect on the early formation of civilizations.
The simplest suggestions would be that any population needs access to fresh water, and that rivers aid in agriculture. Both are true and relevant, but far from sufficient. It is worth observing that the construction of the earliest towns, as well as the most important work in the domestication of crops and of animals, were accomplished neither in Egypt nor in Mesopotamia, but rather in Syria and Canaan between them, and in southern Turkey just to the north. It was there that wheat and barley and other grains became crops suitable for intensive farming; there that cattle, sheep, goats and pigs were bred for human use; and there that early towns like Jericho and Çatal Hüyük were founded. Much of that work was done while the Nile was still far too high to support any kind of population (in essence, there was a Nile without a Nile Valley), while the southern stretches of the Tigris and Euphrates were unable to sustain significant populations because of the capricious, flood-or-famine nature of the rivers.
In these early settlements, rivers were often available, especially in southern Turkey and northern Syria. Even where these settlements did not cling to a stretch of river, water could still be obtained. In much of the Fertile Crescent, rainfall is sufficient to support farming. These towns did not grow into cities, however, and clusters of culturally-related towns did not expand into powerful unitary states. Those developments would happen later, in low-lying regions dominated by one or two major rivers. Again, it is clear that the latter areas offered something new to the development of civilization.
It would be a mistake to think of the historical development of civilizations as an inevitable and obvious step in human affairs, only waiting for the right combination of factors to coincide. The people who built these civilizations did not have a blueprint for complex state societies in mind as they searched for just the right spot to settle. They were, for the most part, agricultural people used to a settled life in circumstances of relatively low population density who began to experience increasing population density and needed to deal with the social ramifications of that development. The reasons for this varied: the Nile Valley saw significant migration from the west as the Sahara gradually dried up, while early cities in Mesopotamia like Ur and Uruk drew more people to them, expanding their spheres of influence and laying the groundwork for more large settlements. Other areas, especially the Indus Valley and the Olmec heartland in southern Mexico, are less well-understood.
In all of these cases, however, agricultural developments that were perfected elsewhere were brought to the river valleys, and flourished on a grander scale. In the Nile Valley, Mesopotamia, and the Indus Valley, crops and livestock from the Near East flourished in much more dramatic form in the great river valleys, especially after irrigation techniques were developed to get maximum use of the rivers’ bounty. Similarly, rice cultivation was developed in eastern and central China, but the impetus to a high civilization occurred in the Yellow River valley in the north. Finally, the naturally-growing Teosinte was cultivated with much effort into the staple crop of Maize, or American corn, in the southern reaches of Central America, but it was at the northwestern limit of the Mexican jungle that this new crop came to support the Olmec civilization that would inspire and inform all of the later civilizations of the Mexican Valley and the Maya territory until the arrival of the Spaniards.
Before irrigation was developed, the river valleys were often inferior sites for agriculture. Too much water was dumped in some places, washing away crops; not enough was deposited elsewhere. The rain-based agriculture of the Fertile Crescent was more useful. With the development of irrigation, however, the floods and silt deposits of the great rivers could be harnessed to dramatic effect. Farming families were capable of generating food for increasing numbers of people. Not only could a family store food for itself, it could also harvest food for others, both now and next year, freeing a larger portion of the population for other tasks, like fighting, or reading and writing, or serving the gods. Complex societies administered by a state of some kind became possible.
Just because these became possible, however, it does not follow that they became inevitable. Especially in the cases of the earliest civilizations, when people did not have the example of preexisting civilizations to guide their choices, people had to decide to participate in this new development, and that suggests that on some level, they agreed that it was in their best interests to participate. After all, if they believed it was not in their interests, they could have left the larger settlements to live in a more familiar way in less densely-populated regions outside of the sphere of control of the new cities. There is some evidence that this sort of thing did happen, at least in the New World, in such circumstances as the end of the classic period of the Maya and the fall of Cahokia.
Evidently, then, the people of the early civilizations saw advantages to gathering in higher concentrations in the river valleys. Part of it must relate to defense. Agriculture and animal husbandry generate wealth in the form of food stores, herds, and immovable improvements like irrigation ditches and levees. Invaders could make off with food and livestock, destroying improvements before leaving. States allowed for more and better-equipped warriors, as well as improvements like defensive walls. That, of course, presupposed larger agricultural surpluses, and these were only feasible in the great river valleys.
Emerging states in the river valleys offered other advantages, too. They could mobilize larger construction efforts, extending irrigation to cover more land. Not only could they generate larger agricultural surpluses, they could also store the surpluses more efficiently. Early administrations staffed by the first scribes oversaw the collection and distribution of such surpluses. Certainly there had to be other forces at work, too – such as the promises of early priesthoods to secure the blessings of the gods – but these fall outside of the question of what the river valleys uniquely had to offer. It is enough that these regions offered a scale of agricultural surplus, and the manpower to manage such surpluses, that made life in and around the new cities somewhat more secure and predictable than life in a more remote village.
Even as populations grew, the scope of new places to settle was constricted. The river valleys are usually pockets of fertility amid inhospitable regions – hemmed in by deserts or mountains. When people needed to move on because of overcrowding, another location along the river became vastly more attractive than anything else, reinforcing the trend of settlement in the river valleys. Cities became interconnected and culturally linked, and regional states emerged over the city level. Transportation on or alongside the river was generally easy, while overland travel away from the river valleys was arduous, especially among those civilizations that did not yet have, or at least use, the wheel. (The Egyptians did not have the wheel in their formative period, and only made significant use of it after the Hyksos brought the chariot to Egypt and demonstrated its military effectiveness. In pre-columbian America, the wheel was known in principle, but was used for no other purpose than children’s toys until the arrival of the Spaniards.) This guided trade along river routes and allowed the accumulation of wealth that could be used for expanded trade networks. It is worth noting that the river valleys generally had great agricultural wealth but were poor in natural resources; however, none of these civilizations had much difficulty in securing the resources it needed from neighboring regions.
River valleys offered unique advantages to expanding settlements and the state societies created to govern and defend them. If not for these advantages, it is questionable whether civilization might have occurred at all, or at least, whether it might have taken a very different form. After centuries of setting precedents, these civilizations served as models for later civilizations, even where the new civilizations began with very different geographic realities than the river valley civilizations. Thousands of years later, the nations of the modern world still live with their legacies.
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