We're the mongols barbarians or builders of the world?

It's difficult to provide a simple answer to that question. There maybe more than one answer. It depends on the views each person has, on cultural and individual values.

The Mongols were seen as barbarians by the Chinese. They didn't follow Chinese customs and social norms, and anybody outside the circle of Chinese culture was taken as a barbarian. Besides, China - Zhongguo, the Middle Kingdom - always saw itself as the center of civilization. After their conquest of imperial China, the Mongols adopted Chinese norms and assimilated to Chinese culture, just as it has happened with other foreign conquerors, which constitutes an acknowledgement of Chinese sophistication.

By their global conquest - the Mongol hordes reached Europe and Southeast Asia - they put together into one political entity many former kingdoms and lands that had had no previous contact with each other. Curiously enough, Mongol expansion was a vehicle of Chinese culture during the Yuan dinasty, founded by Mongols rulers in imperial China.