One of the things specialists have to guard against is the hammer problem. You’re heard the saying about “when all you have is a hammer, everything looks like a nail.” When your specialty is, oh, economic history focusing on commercial trade in eastern Europe in the Long 19th Century, diplomacy and wars and politics and larger social changes can start to look as if they were caused by, shaped by, or at least strongly influenced by trade and commerce. As an environmental historian, I have the same tendency. I found myself growling at Dr. Cunliffe’s book last month asking “What about climate shifts? What about environmental change as a driver? Come on, where’s the environment?” In his defense, he’s trying to cover an area from Vienna to Tripoli to Sri Lanka to Mongolia and back, from 20,000 BC to AD 1500, without writing a book so large it needs a little cart to carry it around. But climate did play an important rule in some very large events, at least geographically large.
Archaeologists have become pretty confident that, in general, with a lot of local exceptions, gathering and hunting was slowly replaced by gardening and hunting and gathering, then farming and hunting, then farming. People shifted back and forth at times, going from gardening back to moving around and hunting and gathering, or moving around with herds of domesticated sheep and goats, or some people staying put and farming and making goods while others took the sheep, goats, and pigs to summer pastures and brought them back. In the area north of the Black Sea, you had farmers and gatherers living on different sides of a river at the same time, or herders and gatherers. It is not a nice straight progression like my old textbooks used to show.
However, one thing that has had archaeologists and anthropologists puzzled was always what caused the shift? In some cases it seemed to be that the gatherers observed that the settled people had more food and better material goods, and so they adopted the settled lifestyle. Except. Except there were a few cases where settled people appear to have looked around and decided that time had come to change, and they returned to being nomadic pastoralists. In one interesting situation, at the transition between the Stone Age and Bronze Age, a culture built walled settlements in low, marshy areas, and mined as well as herded. Now, fortifying the low places and leaving the high ground undefended strikes a lot of people as being a touch odd, if not really dangerous and risky. Why the shift?
Around 3000-2500 BC the climate shifted, becoming cooler and moister. The moist part is important, because it meant a lot more of the swath of grasslands that runs from Budapest to Beijing became usable by herders and horsemen. Trade increased as well, and metallurgy spread from the Balkans through Anatolia and east, as well as west. Horses and wagon-using herders speaking Proto-Indo-European also spread. At the same time, the farming culture of Old Europe, centered in the eastern Danube watershed, started to shift, then faded away. Actually, in terms of how long it had been around, it seemed to go “poof!” and disappear in a long eye-blink. Why? One theory, still popular in some circles, was that the [evil] patriarchal, hierarchical pastoralists did-in the egalitarian goddess-worshipping farmers. While that may have happened in a few locations, the farmers seem to have been having trouble because of the increased precipitation, lower evaporation, and cooler temperatures. Marshes and wetlands expanded, floods grew larger and more common, and marginal land became unfarmable.
A thousand years or so later, the process shifted once more, and a warmer, drier period began. Forests retreated north, and desert expanded into steppe. Those marshy areas that had regular water and grazing became very valuable, enough so that in at least one case, the horse-sheep-goat-cattle herders built fortified settlements to protect their claim to the wetlands. They also smelted copper and some copper alloys, trading for grains and other goods. That lasted for a while, then shifted again.
Around 1000-500 BC, wet and warm spread. And some people, a group of people with cultural ties to the peoples of Siberia and Manchuria, finally said “Forget this. We’re going all horse, all the way.” And the first horse nomads, whom the Greeks called the Scythians, emerged into the western steppe and into history. They would be followed a few hundred years later by the Huns, then the Avars, then the Magyars, then the Mongols. These are what Dr. Cuniliff calls “predatory nomads,” the classic light cavalry who terrorized the settled peoples of Eurasia.
In all these cases, shifts in climate either made expansion possible or necessary. When people depend entirely on what the environment provides, when the environment changes, they have to adapt or move, or they might not survive. Was climate change the only driver? No, it very rarely is, especially the later in time you go (i.e. the closer to modern). But it made things possible, or encouraged change, or in some cases pushed people to give up one way of life for another.