Which group used the stirrup, skilled horsemanship, and siege warfare techniques to conquer much of asia and part of europe in the 12th and 13th centuries? (1) japanese (3) persians (2) vikings (4) mongols

I believe the answer is: 4. Mongols

The Mongols started to rise into its peak when a king named Gengis Khan rose into power. He require his military to learned advanced technique of horsemanship and siege warfare and managed to conquered approximately around 16% of world's territory and about a quarter of world's population. Even until this day, the Mongol Empire is still regarded as the largest empire that ever exist.

answer; (a) he was a u.s senator for 38 years;

the name of the theory is landmass theory.