We see that horses, which were first domesticated in Eurasia, began to spread rapidly soon afterwards in the 3rd millennium BC. Horses and their roles included agricultural work, as pack animals, and as instruments of war. By the mid-2nd millennium BC, horses begin to have an even more dominant role in large-scale, complex society warfare. In the early 1st millennium BC, elite soldiers and horsemen replaced charioteers and became the elite soldiers of the battlefield until the early 20th century AD, even after innovations such as gunpowder and rifles. Key innovations such as the stirrup and harness facilitated the dominance of horses as beasts of burden and warfare
for several millennia and until the 20th century AD.