In less than 70 years, beginning around 560 B.C. Persia’s Achaemenid Kings brought together all the disparate nations of the ancient Middle East into a single political unit.
Achaemenid egemony reached its peak after 522 B.C. under Darius I. The empire’s nucleus had been formed by earlier Achaemenids who, from a base in the region called Persia, laid claim to such ancient kingdoms as Media and Assyria.
Cyrus the Great created the actual imperial structure and extended his control to all the land between Bactria (current North Afghanistan) and Phrygia (current Anatolia in Turkey).
His successor, Cambyses II, absorbed Egypt. Then Darius pushed Persian dominance to its limits. By the end of his reign, the 1.600 mile long Royal Road connecting the imperial centre of Susa with Sardis in Lydia (current Turkey) was completed, as was the canal that joined the Mediterranean with the Red Sea.
The greek historian Herodotus mentioned 28 regions that figured in Persian history: 20 of these were satrapies, or subject states.