Why do groups of people relocate, especially in pre-modern times? There’s always a reason for groups to move. Individuals might wander on a whim, be it wanderlust, the desire to escape relatives, or just to see if the grass really is greener “over there.” But when cultures and tribes up sticks and head out, there’s always a push and a pull. One of the things I’m starting to tease apart when I look at the big-picture history of Europe and Southwest Asia is the pushes and pulls behind population shifts. “The Huns were moving, so these other people moved.” OK, why did the Huns move? For a long time we didn’t know, because the written records didn’t include interviews with various historical characters or groups. However, in the past forty years or so, environmental history has provided a few new reasons for pushes, at least.
Keep in mind, weather and landscape are not deterministic. That is, very, very rarely can you point to one climatic event or geological thing and say, “This is why the Seljuk Turks left Central Asia” or “this is why the Anasazi left the area to become [various tribal groups].” Sometimes you have to pull together bits and pieces from archaeology, geology, palynology and tree ring and stalagmite studies, epigraphy, business records, government reports (if they exist), and look for patterns, then try to sort out what caused the pattern. And sometimes you bring a new approach to old data and say, “Hey, you know, I wonder if the reason for [thing] could be related to [other thing waaaaay the heck over here]?” You know, like the rash of very large range fires in the late 1800s in the Texas Panhandle being related to a combination of wetter weather and far fewer grazers keeping the lawn clipped. So there’s a lot more grass, in more places, so if it dries out and a spark gets tossed by something, well, you get Interstate Grass Fires of Unusual Size.
So, pushes and pulls. In the late AD 900s – early 1000s CE, while western Europe was basking in the Medieval Warm Period and starting to build giant cathedrals, hold enormous trade fairs, and enjoy the good weather, Egypt, eastern North Africa, and as far east as Afghanistan started with drought, then a series of cold years that led to famine, disease, civil unrest, attacks by nomadic peoples (Bedouin) on cities, and eventually the Seljuk Turks moving out of the Steppes into Southwest Asia. Their behavior triggered the Southern Crusades. This pattern also put pressure on the Byzantine Empire and explains the renewed push by the Arabs and Persians against the Byzantine borders, further weakening them.
The push for the Seljuks was the terrible cold weather that caused the grass to die, and their animals as well, forcing them to relocate. The pull was a political vacuum in Mesopotamia and warmer weather with better forage conditions. The Byzantines were not in a good position to chase anyone out of the region at that point, neither were the Fatimids of Egypt, so the Seljuks stayed, and eventually helped pull the Ottomans out of the Pontic Steppe, and we all know what happened then.*
Back up five hundred years or so, and we see something similar in Northern Europe. Why were the Visigoths, Ostrogoths, Burgundians, Huns, Bulgars, Avars, Franks, and Vandals all moving west? Dry weather in the Eurasian Steppes was pushing them, possibly an outbreak of plague as well, and the resources and relative disorganization of the Roman Empire (both halves) provided a pull. Once the Western Empire could no longer defend against eastern pressure, the Germanic and Slavic people flowed in, driven now by cold and dry or cold and wet episodes farther east. After whatever happened in the early 500s (possibly huuuuuge volcanic eruption where the Sunda Strait now sits), the weather turned very bad in Europe, forcing further population shifts (the push) into milder or at least not-as-bad areas (the pull). Plague and hunger dropped the population in some areas, opening space for migration (Britain, possibly). Come the 800s, things are improving in the West, and too many young men in Scandinavia need a job, so they start trading and Viking. Drought in the eastern steppe pushes the Magyars, who push others, who appear in the western historical records as “barbarian nomads.” Charlemagne got to deal with them, and with the Saxons, and a few early Vikings.
North America shows something similar but in the 1300s. The Little Ice Age caused major drought in the American Southwest and affected weather in the central part of the continent as well. At the same time, the people of the Cahokia cultural complex found themselves having problems, partly because of deforestation. They shifted away from the large-centrally-managed culture and back to smaller, scattered groups, eventually moving south and east. This pushed other peoples, who pushed more people, and so on.
China in the 1600s – Bad weather, bad management, disease outbreaks, civil unrest from all of the above. Nomads moving because of the cold and harsher weather push on the borders, until someone invites a group in to solve the local problem and then leave. They didn’t leave. They became the Qing Dynasty.
Pushes and pulls. They are a lot more complicated than what I’ve sketched above, because I’m just thinking about some of the easy to spot episodes, the biiiiig ones that historians can point to and say, “See, this is what I’m talking about.” One of my very long-term projects is looking at the pushes and pulls in Central and Southeastern Europe, and comparing those patterns and responses to borderlands elsewhere. There are some similarities — we’re talking about humans, after all — and echoes, but also differences.
*”Prinz Eugen and Jan Sobieski, if you can hear this announcement please pick up the white courtesy phone for a message, Prinz Eugen and King Jan Sobieski . . . ”