Co-Geeking

In a previous post, we considered the sizes of migrating groups in antiquity. We can probably dismiss any idea of hundreds of thousands of people pouring across the Roman Empire, but the challenges of moving even 10,000 people long distances in ancient conditions are significant.

People need things: clothing, bedding, medicine, tools, weapons, and most of all food and water. People on the road have to make do with less, but some things are still essential for survival and must be either carried with the group or found along the way. The more stuff people carry with them, the slower they move and the longer it takes for them to get to a place where they can settle down and start rebuilding; the faster people move, the less they can carry with them and the more they have to either rely on finding what they need along the way or suffer without. The logistics for moving a large group of people are always a compromise between stuff and speed.

The amount of stuff people can carry is limited. A healthy adult can typically carry around 20-25 kilos and still manage to walk long distances. Trained individuals can carry more, but people who can manage this feat are few, and in a large group will be outweighed by the young, elderly, sick, and disabled who can carry less. Animals can add to carrying capacity, but they also create greater demands for food, water, and medical care; carts or sledges can add capacity, but they are slower and limit what terrain a group can cover. The best way to carry large amounts of stuff long distances is over water, but this also limits what routes a group can take.

Healthy adults traveling by foot in good conditions can typically maintain a walking pace of about 4-5 kilometers an hour, and keep up that pace for hours at a time, covering between 20 and 40 km a day, but large migrating groups were not all made up of healthy adults and did not always have the luxury of traveling in fair conditions. A large group traveling across country would have been slow, and the larger the group, the slower it would have traveled.

The most important supplies for a traveling group are food and water. In extreme circumstances people can do without bedding, tools, weapons, even clothes, but if they run out of food and water they are done for. The average adult needs about 1.5 kilos of food and 1.5 liters of drinking water every day to sustain the exertion of long-distance travel by foot. Fresh water is available from wild sources across many parts of the temperate world, but large groups can exhaust local supplies. Some amount of food can be foraged or hunted in the wild, but there are very few landscapes anywhere rich enough in wild food sources to sustain a group of 10,000 while still allowing them time to make significant progress on their journey. A large group of people traveling across an ancient landscape had only two practical choices: carry food with them, or acquire it from the farms and fields of the regions they passed through.

Carrying your own food for a journey is helpful, but it has limits. Considering that typical adult carrying capacity is 20-25 kilos, and an adult needs 1.5 kilos of food a day, even a person carrying nothing but food can only carry about two weeks’ worth of rations. Carrying that much food means sacrificing any other gear, even the tools to prepare and cook the food with. In a large group including young, old, sick, and disabled, some people have to carry food for others. Even in the best conditions, a large group traveling overland could carry its own food for only about 10 days. Adding pack animals does not help the situation, because the proportion between what a horse, donkey, or camel eats and how much food it needs to sustain itself is the same as for a human being: even a pack animal loaded with nothing but food will eat up its entire cargo in less than two weeks. Allowing animals to graze extends the number of days they can go, but also slows them down. A large group traveling for 10 days might just be able to carry all their essential supplies with them. 10 days of travel would allow them to cover a distance of at best around 200 km, but in practice most migrating groups could not maintain such a speed. Realistically, any large group undertaking a long journey would have to acquire food (and other supplies) from the regions they traveled through.

Acquiring supplies locally is its own challenge. Ancient agriculture was of limited productivity. Most ancient farming towns did not produce a large surplus. Large migrating groups were unlikely to be carrying with them either trade goods or cash sufficient to buy or barter for all the food they needed (unless they were willing to sell off some of their own number as slaves). Any large migrating group probably reached a point, willingly or not, where they had no option but to take by force the food they needed to keep going. Such raiding surely provoked the local population to either fight back or hide their food supplies, either of which was another problem for the migrating group that slowed down their travel and stretched their resources.

Now, all of these problems did have solutions in ancient conditions. They are essentially the same problems that an army on the march faced, and there were plenty of armies in the ancient world, some of which may even have numbered in the hundreds of thousands. Armies, though, had two advantages that migrating groups did not: 1) they were mostly made up of healthy adults, and 2) they had the financial and logistical support of a state behind them. Groups of people that did not have these two advantages faced serious challenges if they wanted to move long distances en masse.

Next time, we’ll put together what we know about the realities of numbers and logistics to see what we can say about what a “barbarian migration” might have actually looked like.

Image: Huns via Wikimedia (1910; painting; by Georges-Antoine Rochegrosse)

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