Iran as a civilization begins with the Achaemenid Empire founded by Cyrus the Great in 549 BCE. Cyrus overthrew the Median king Astyages, captured the Babylonian capital in 539 BCE, and created the largest empire the world had yet seen. Rather than destroying the cultures he conquered, he embraced them. He allowed subject peoples to keep their customs and religions. His famous decision to free the Jewish captives and let them return to Jerusalem earned him the title of “Savior” in the Bible. His successors, including Cambyses, Darius, and Xerxes, built on this foundation. Darius created the satrapy system of regional governance, established a professional bureaucracy, and built the famous Royal Road stretching 1,677 miles with relay stations for messengers. Herodotus praised these couriers, noting that nothing, neither snow nor rain nor heat nor darkness, stopped them from delivering their messages quickly.