What contributed to the decline of the great bison herds?

in 550 b.c.e. cyrus the great, the leader of the persians, conquered the medes and united the iranian people under one ruler for the first time. cyrus became the first king of the persian empire and went on to establish one of the largest empires in world.

imma have to go   the third option

sorry if i am wrong hope this

if i am right plz give me brainliest

the answer should be founding brothers. i hope i you!