By the late-fourth century the later Roman Empire experienced an invasion by nomadic peoples from Asia – the Huns. This invasion would intensify in the years 447 to 453 under the Hun leader Attila. This would be the start of several invasions into Europe from the East during the Middle Ages, ending with the Mongol Empire.
While the arrival of the Mongols in Eastern Europe is better known, historians have few clues to why the Huns and Avars migrated from Central Asia. A recent article by Edward R. Cook, a climate research specialist at Columbia University, offers some new insights.
In his article, ‘Megadroughts, ENSO, and the Invasion of Late-Roman Europe by the Huns and Avars’, Cook analyzes records related to the El-Nino Southern Oscillation – a periodic episode when warmer waters off the west coast of South America cause significant climate change across the Pacific region. Researchers have been able to track the effects of the El-Nino Southern Oscillation system going back over two thousand years by examining tree ring patterns from both New Mexico and New Zealand.
Using data from these records and a couple of surviving ancient tree ring specimens from North-Central China, Cook suggests that three megadroughts struck Central Asia between 360 and 550, the first of which was the worst drought in the history of the region in the last 2000 years.
Cook notes that the El-Nino Southern Oscillation causes a weather effect known as the La Niña, which in modern times disrupts rainfall in Central Asia during period of March to June. Cook writes, “Its conceivable that this period of intense aridity spurred the nomadic Huns to seek better living conditions westward of their home territory to as far as the eastern Roman Empire, with invasion and conquest a natural part of this migratory process.”
The first and worst megadrought took place around 360 AD, followed by a second decline starting in the 430s, reaching its driest period around 480.”Interestingly,” Cooks adds, “the fourth and fifth century megadroughts are also separated by about 50 years of mostly above average wetness. This ‘pluvial’ period is likely to have produced better living conditions for the Huns in their central Asian homelands, thus allowing them to build up their capacity for the invasion of late-Roman eastern Europe.”
The article also notes that another megadrought occurred around 550 AD, when another nomadic group known as the Avars made their way into Eastern Europe. Cook explains, “While not as extreme as the two previous megadroughts, this period of dryness may again have incited the nomadic Avars to migrate westward in search of better conditions and plundered wealth.”
The article ‘Megadroughts, ENSO, and the Invasion of Late-Roman Europe by the Huns and Avars’, appears in The Ancient Mediterranean Environment between Science and History, edited by W.V. Harris, and published by Brill. This collection of eleven essays that climate and environmental change in the Roman World and Early Middle Ages.