In the interior of Asia lies the vast sea of grass, the steppe.
No place on earth is as poorly understood and yet has had so great an impact on human history. The Celtic and Indo-European languages originated here.
The silk route passed through here.
The Silk Route
Two critical innovations distinguished the nomads of the steppe. The first was the domestication of the horse. Nobody knows when this started, but by 4000BC, the steppe dwellers had large herds of horses. The second was the domestication of cows and goats. The milk from these animals provided a mobile and perennial food freeing them from the ties of agriculture. Not only could they move, they had to move. Large herds ate up grass much faster than it could re-grow in the semi-arid grassland.
This mobility meant the sedentary life of agriculturalists was closed to them. Wherever agriculturalists settled into a stationary society, they needed a stable government. Government required taxes and records for trade and boundaries. Records required writing. The pastoral nomads of the steppe never settled and never developed an advanced written culture. They did however have a rich oral tradition.
The Vedic hymns which are venerated to this day are believed to have originated around 1500BC when the nomadic Aryans migrated from Central Asia into the Indian subcontinent. For generations they were transmitted orally before being written down. Indeed an advanced system of memorization and error checking was devised to ensure these hymns could be remembered exactly. Unsurprisingly, cows and horses feature prominently. Horses are mentioned 200 times in the Vedas. The Vedas state that the milk of a cow is equivalent to ambrosial nectar and that ghee derived from cows milk is the best of all libations poured onto the sacred fires of brahmins.
Vedas written in Sanskrit
Another result of a nomadic lifestyle was that the population density of the steppe remained low (and remains low till today). A pastoralist needs much more land to feed his animals than a farmer needs to feed his family. But with their horses, the steppe nomads could cover vast distances quickly and concentrate in huge numbers.
Ottoman horse archer
This is how the archetypical image of the vast barbarian horde was formed. Whenever a strong leader (like Attila the Hun or Genghis Khan) could unite the tribes under him, he would have a vast and mobile force. Their neighbours, the Chinese and the Romans understood this and took care to play chieftains one against the other keeping them fragmented.
No civilized commander other than Alexander the Great had much success in trying to conquer them. Alexander himself only succeeded by making alliances and marrying the Scythian princess Roxanne.
Marriage of Alexander and Roxanne by Sodomar c.1517