They didnt have really good technology
The Mongols (once the various tribes were united under Genghis Khan, born Temüjin ) used their expertise with horses to form mobility on the battlefield to their advantage.
The Mongols incorporated Uyghur Turks into their military forces.
The mongols was so military successful because strategists and tacticians. This were tough people.
mongols
to prevent a rebellion by mongols
That the American system was designed to take advantage of new technology
The Mongols did not execute bugs. The Mongols were a nomadic group of people from Central Asia who established one of the largest empires in history. They were known for their military conquests and brutal tactics, but there is no historical evidence to suggest that they executed bugs.
It was the Mamluks. A Mamluk was a soldier who converted to Islam, over time they became a powerful military. It was one of the only battles the Mongols lost. Wikipedia: Mamluks
The first appearance of a military patronage state was around 1258 after the Mongols sacked Baghdad from the Muslims. This was shortly after the Crusades and the Muslim armies were fatigued and weakened. No one expected the Mongols to come through the way they did and defeat one of the great powers of the time. As a way of maintaining control over the territories they had recently acquired the Mongols developed what would come to be known as a system of ruling called "military patron states." Because the Mongols were nomadic herdsman they would pillage a city (often with devastating death counts and brutality) and then move forward to the next city. The conquered city was then left to rule itself with one catch, they had to pledge patronage to the Mongols military force.
The Mongols employed several advanced military technologies to attack walled cities, including siege engines like trebuchets and battering rams, which enabled them to breach fortifications. They also utilized gunpowder-based weapons, such as early cannons and explosive projectiles, to increase their destructive capabilities. Additionally, the Mongols were skilled in psychological warfare, often using tactics such as feigned retreats and the threat of overwhelming force to intimidate defenders and encourage surrender. Their adaptability and innovative strategies made them highly effective in siege warfare.
The new technology gradually changed military strategy. Because the rifle and the minié could kill far more people than older weapons, soldiers fighting from inside trenches or behind barricades had a great advantage in mass infantry attacks.
A loss at Vienna ended their invasion of Europe, after that they retired through Hungary to Russia.