Question

The mongols built one of the worlds greatest empires

Answer 1

The Mongol empire (1206-1368) spanned from Eastern Europe across Asia. The empire emerged from the unification of Mongol and Turkic tribes in today's Mongolia and grew through invasions after the proclaiming of Genghis Khan in 1206 as ruler of Mongols. 
The Mongol empire was the largest contagious empire in the history of the world, and the second largest empire in history, after British empire.
Under the Mongol technology, different commodities and ideologies were spread and exchanged across Eurasia. They were master engineers who used every technology known to man. 
They built a spectacular international postal system and created standardized notes and paper currencies before Europe created its own.