Answer:
The Mongols were highly tolerant of most religions during the early Mongol Empire, and typically sponsored several at the same time. At the time of Genghis Khan in the 13th century, virtually every religion had found converts, from Buddhism to Eastern Christianity and Manichaeanism to Islam. (Wikipedia)
So they were really kind of people who accepted religion. If you mean contribution, then they were the ones who kinda started the black death in Asia. They herded cattles and kind of contributed to modern switch farming. So they moved to different places as their cattles were eating the grass.