Eyre Lines

Many moons ago, my son was presented with an essay title for his History GCSE, which was on the causes of the First World War. He decided to talk to me about it.

The immediate cause was, of course, the network of alliances which had grown up between European powers which was intended to create a sort of detente, a situation where no-one could afford to be aggressive because of the likely invocation of alliances bringing in the then “big players”. History records, of course, that an agression by one of the more minor players, Serbia, via a terrorist act, resulted in the whole structure being mobilised – as were troops all over Europe. This is beautifully lampooned in a joke comparing the whole thing to a bar fight. Current commentators worry, not without reason, about minor players like the Baltics and Ukraine drawing Nato into a world conflict in the same way.

Looking to expand his appreciation of the broad sweep of history, I encouraged him to think about why there were competing ethnicities and religions in the area, and we traced that back by stages. His eventual essay (which got him an A*) stopped at Trajan’s Dacian wars – he was probably sensible in not going all the way to where our discussion ended, something like four hours after we started.

However, we didn’t stop there in conversation. The Dacian wars were at least in part caused by population pressure from the east. It was thus one of a series of waves of pressure on Europe from that direction, as tribes moved west over the whole area from Mongolia to the borders of Europe, each pressed by those to the east of them. Sometimes, the more eastern tribes actually managed to conquer and form alliances well enough for their members to arrive in Europe itself; the Huns were the first, followed by the Mongols; the Turks were another. In Trajan’s time, however, the Dacian movement was a knock-on effect. The Dacians were pressed by those east of them, such as the Scythians.

Why, we asked, did this set of waves of migration actually occur, and why hadn’t they happened earlier in the history of the Roman Empire? My best guess at this rested on climate change. Where there was a relatively wet, cool period, the homelands of the more eastern tribes and their natural raiding areas (largely China) became more fertile, producing an increasing ability to support population. The period in question was marked by a set of cycles of cool wet weather followed by warm dry weather, though, and when it turned warmer and dryer, the population in the east couldn’t be supported there any more. At the same time, warmer, dryer weather dried out the immense areas of marshland along the Dnepr river (including the well known Pripyat marshes) and lesser ones along the Don and Vistula rivers. What was, in wet weather, a hostile landscape for horse-warriors became plains which were ideal for large mounted operations, and effectively created a highway all the way through to the Balkans in the south and Germany in the north. It wasn’t just Europe which suffered this way; the Middle East had its own waves, for example that under Timur Leng which ended the golden age of Islam, that under Ghengis and Kublai Khan which replaced the native Chinese empire with a Mongol one for centuries, and that under Babur which founded the Mughal Empire in North India.

The ultimate cause was, therefore, changes in climate, which interacted with the predominantly horse-oriented nomadic culture of the eastern part of north Asia to produce very massive population movements.

I’ve been reminded of this by reading a New York Times article on how climate change produces migration. We focus a great deal when talking about Syria or Yemen on political issues, but the map at the beginning of that article makes clear the unacknowledged fact that from Syria down into the Arabian Peninsula, climate change is affecting the ability of the land to support population, and that is going to produce increased competition for the increasingly scare resources, wars and both economic migrants and those fleeing war and civil disorder. The same goes for a swathe of land through Sudan to the horn of Africa, and for areas in central West Africa as well, those being the source of much of the migration trying to cross the Mediterranean from the more Western points such as Libya. Americans should notice the intensity of red dots in the north of South America and in Central America.

Rome, of course, eventually collapsed in the fact of these waves of migrants, unable to stem the tide; the Goths, Vandals and Franks were pushed (largely by the Huns) westward, and took down the civilisation in the Western Empire; in the Eastern Empire it was the Turks in a later wave who dealt the coup de grace, though there had been an earlier Arab expansion (which I can’t connect to climate change, but which may well be another instance) which had done immeasurable damage first.

We’re a lot stronger than Rome was in Europe and America, of course. But we should perhaps wonder whether we can actually get away with merely building a wall along the Mexican border and fences along the long European border to the east. The Chinese had a frontier-long wall as well…