People are looking at the phenomenon of horse-nomadism as a form subsistance which leads to certain convergencies in life-style and social organisation.
One of the primary effects is that pastoralism, the need to travel with and defend, herds of animals, produces skills and abilities that are extremly militarily useful as well.
Horse nomad society obviously wasn't possible before the domestication of the horse as a riding animal. First to make their appearence were the Skythians, whom the Greek knew quite well. They seem to be regarded as pretty much European, whatever one wants to put into that term precisely.
You then get at least partially horse-nomadic groups getting into empire-building in the form of Medes, Persians, Indo-skythians, Bactrians etc.
What they all have in common are horses, livestock and a way of life structured around these.
Then there's another crucial aspect if horse-nomadic societies: Being primarily nomadic, they struggle to produce a number of things and commodities that sedantary agriculturalist societies provide - be that Chinese, Mid Eastern or European agriculturalists. I.e. the lifestyle of these nomadic peoples would be in the long run untenable, if they weren't able to interact with the agricultural societies around the central Eurasian plains, to get certain crucial goods from them.
Now, that interaction can and did take a certain number of forms. Provided the agriculturalists were prowerful and well organised, the nomads would tend to need to adopt a relatively peaceful attitude and trade for things.
However, horse-nomad society working like it did - meaning a life-style that built and honed skills that were individually useful for a warrior, while the collective responsibility for herds of animals meant a need for organisation and group-action - at some point some enterprising nomad, looking at the agiculturalists somewhere, would say to his mates: "Those look soft enough. I bet we could just ride right in and take whatever we want, and kill anyone who tried to stop us. What'd'ye say?"
And that is the basic situation which set up about 2000 years of Eurasian history of see-sawing between the sedantary agriculturalists along the coasts basically, and the successions of horse-nomadic empire builders that ruled over the central Eurasian grasslands. It was a constant ebb-and-flow of new enterprising nomadic empires, and the agriculturalists beating them back, or just assimilating them as the bastards last to arrive aspiring to form the ruling elite, as the case might be.
Even if the words were formulated by the Greeks on behalf of the ancient Persians, there seems to have been a fairly rapid realisation on the part of these conquering nomads, that at the point of settling down to enjoy the fruits of their conquests, they were already sowing the seeds of their own demise. Forget which of the Mongols supposedly said it, but a salient observation is that one could conquer the world on horseback, but not rule it from there.
The pinnacle of horse-nomadism were obviously the Mongols, who pushed the concept further and more radically than anyone ever before. In essence the gambit was a kind of attempt at creating a form of permanent, institutionalised system of raiding-as-permanent-conquest of all these agriculturalist societies they came across. Very impressive. Extremely destructive. And not even the best shot by the Mongols was destined to last.
In the end, it's all about how societies support themseves - subsistance models and economy - and bugger all about ethnicity, or "race" for that matter.
What we then got in history was a situation transiting from the Middle Ages to the Early Modern Age, where the situation in the agriculturalist societies changed sufficiently to make them too powerful for the horse-nomads to be able to effectively challenge, like the previously had.
A great point of view from a friend at historum at the rule of the horse nomads/tribals and their leaders attila,genghis,timur.
Once the agrarian plain based societies began to deploy gunpowder en masse and negated their cavalry/archery advantage they were finished.So they had their time in the sun and with the coming of industrialization were rendered obsolete.
