This is a bit of a rewrite an older answer of mine that addresses a related question, along with parts of an answer I never posted about Plains Native American hoof care. I do wish I had better details on the specifics of 13th century Mongol hoofcare practices. Hopefully someone else here can fill that in better.
The Mongol cavalry that conquered Kievian Rus and dominated Polish heavy cavalry in the 13th century did so barefoot. In fact, modern Mongols on the steppe don’t shoe their horses either. This picture shows a Mongol pony getting a trim. Why the trimmer feels it necessary to down and hobble the horse to do this, IDK. But the horse is clearly barefoot, and has beautiful feet (from an equine podiatry perspective). In modern Mongolia, they still run a 1000 kilometer barefoot horse race, the Mongol Derby, meant to recreate and celebrate the postal system Genghis Kan introduced in 1224.
First, we should differentiate between horseshoes, usually metal devices nailed to the bottom of a horse’s feet, and boots, which are like human shoes secured to the foot with laces, straps or other such devices. Boots are much older than shoes, and protect the sole of the hoof from stone bruises and the like. They can be made from a variety of materials, including iron, but most varieties are more flexible and shock absorbent. Many non-shoeing communities use boots to deal with wounded feet or unusual conditions. I have never actually seen Mongol hoof boots documented, but I have seen such artifacts from other nomadic horse cultures, such as Plains Indians. Lewis and Clark made buffalo hide “Mockersons” for the barefoot ponies they procured on their expedition. Nailed on iron shoes are a whole different animal, primarily designed to reinforce the hoof wall. These walls needed reinforcement in Medieval Europe because the preeminence of permanent fortifications moved military horses inside, into stalls. Horse feet are delicate systems that require constant movement to function properly. The triangular, rubbery “frog” at the rear of the hoof expands and contracts as the horse transfers weight on and off the foot. This allows for better traction, shock absorption, and also acts as a blood pump, assuring good blood flow through the “digital cushion” inside the hoof. Actually, current research suggests that this pumping action is an integral part of the whole circulatory system, and that shoeing horses places extra strain on their hearts. Walking also wears the hoof into a healthy shape. When horses are not allowed to roam, and instead are kept in stalls, their feet react very badly. A horse standing in its own waste all day, rather than wandering over varied terrain, will start to lose hoof integrity. Their feet literally fall apart. Although the Classical Greeks did not stall as much as later Europeans, and had a nice dry climate, it was enough of a problem for them that Xenophon wrote about it,
“But if food and exercise with a view to strengthening the horse's body are matters of prime consideration, no less important is it to pay attention to the feet. A stable with a damp and smooth floor will spoil the best hoof which nature can give. (7) To prevent the floor being damp, it should be sloped with channels; and to avoid smoothness, paved with cobble stones sunk side by side in the ground and similar in size to the horse's hoofs. (8) A stable floor of this sort is calculated to strengthen the horse's feet by the mere pressure on the part in standing. In the next place it will be the groom's business to lead out the horse somewhere to comb and curry him; and after his morning's feed to unhalter him from the manger, (9) so that he may come to his evening meal with greater relish. To secure the best type of stable-yard, and with a view to strengthening the horse's feet, I would suggest to take and throw down loosely (10) four or five waggon loads of pebbles, each as large as can be grasped in the hand, and about a pound in weight; the whole to be fenced round with a skirting of iron to prevent scattering. The mere standing on these will come to precisely the same thing as if for a certain portion of the day the horse were, off and on, stepping along a stony road; whilst being curried or when fidgeted by flies he will be forced to use his hoofs just as much as if he were walking. Nor is it the hoofs merely, but a surface so strewn with stones will tend to harden the frog of the foot also.”
Xenophon is telling us that if we can’t let the horse wander around foraging and living a healthy horse lifestyle, we should simulate it as much as we can. For urban horses, that turned out to be less popular than nailing their hoof walls into shape with iron bands. But horses kept by nomads, or rural agrarians with a lot of space, can live like wild (technically feral) horses. The nomadic horse cultures of the Eurasian steppe had a near ideal lifestyle for healthy horse feet. I actually have some experience with this type of equine husbandry. When I was a kid, I had rancher friends in 1970s Wyoming. They did not stall or shoe their horses. Their horses lived much like Mustangs, free to roam hundreds of acres of varied terrain. Their only amenities were large windbreaks erected in each field. Horses are very sensitive to wind. They can remain happy and healthy in very harsh cold, rain and snow, so long as they can stay out of the wind. Later, I kept my own horses the same way. For a nomad, living on the plains or steppe, shoes would cause far more problems than they would solve. Keeping horses shod is a constant struggle. The lack of cushion from the natural expansion and contraction of the hoof contributes to joint problems. I have known farriers that tried to minimize that by only nailing the front of the shoe, but then they are easily thrown, sometimes damaging the hoof wall in the process. Shoes would reduce a pony's sure-footedness, since hoof flexion contributes to traction and smooth iron doesn’t. Modern reining horses, prized for long sliding stops, have the biggest shoes they can fit on their hind feet, to reduce traction. And again, lack of hoof flexion can cause structural problems in the hoof. Today there are rubber, glued on shoes, which in theory should minimize all these issues. But they are not widespread and I have no experience with them. And back in 1876 W.E. Yates filed a US patent for a rawhide shoe.
“Previously to this invention such shoes have been made of iron, and have been more or less rigid, and the jar when the shoe has struck the ground has had an injurious efiect [sic] upon the hoof and adjacent-parts; and such shoes have been liable to slip upon asphalt and other pavements. According to this invention the shoes are made wholly or partially of untanned animal hide, such, for example, as the well-known buffalo hide.”
He went on to describe the deficiencies of previous rubber and leather devices, so clearly the limitations of iron shoes were widely understood, or there would not have been such experimentation.
In short, shoeing is a tradeoff, and one that does not favor semi-feral horses living and working with plains or steppe nomads. People who keep horses in semi-feral herds, like the Mongols and I, don’t typically shoe.
War Horse: A History of the Military Horse and rider, Louis A. DiMarco
On Horsemanship, Xenophon
The Natural Trim: Principles and Practice, Jamie Jackson
Journals of the Lewis and Clark Expedition, Meriwether Lewis and William Clark
Indian Horses and Horsemanship, J. Frank Dobie, Southwest Review, Vol. 35, No. 4
