Mongols were the first nation to build an army of soldiers, rather than an army of feudal warriors and mercenaries. 

Mongol soldiers fought as well disciplined formations and did not seek individual glory. They had no superfluous customs (like inviting enemy champions to single duels) or religious rituals to perform before a battle. 

Their equipment was modest yet effective, they were not burdened by heavy armor, they did not decorate their weapons with gilding or gemstones or wear elaborate helmets like some European knights did. 

Indeed their soldiers had a surprisingly modern look: In old paintings (and modern illustrations) they look like how you expect an early 20th century cavalryman would look: A simple overall coat, a sabre, riding boots, a water bottle, an helmet or felt hat. Nothing more.