When Sumerians used these in war, they had 4 wheels & were drawn by big-eared equines called onagers
The four-wheel Sumerian war chariot is often called a "war wagon" to
... [DOC] [TLE] HORSES AND DONKEYS | Facts and Details [PAR] They were ridden and used as beasts of burden and were vital in transportation, 
... America are descended of domesticated horses that had been released in the 
wild.