I am surprised how the Achaemenids have received very little mention in this thread. Just looking at the relief-work at the Persepolis palace complex with all the depicted dignitaries arriving to bring tribute reveals how this tapestry was interwoven across cultures, religions and physical differences, all organized under a single political super-structure and framework, with its "moving parts" being propelled by lingua francae, and the vessel being the royally issued currency, the dareikos stater; otherwise known as the Persian daric.

Great canals were dug, great bridges constructed, grand roads established and ambitious expeditions both by land (Scylax of Caryanda) and sea (Sataspes); it is in the Achaemenid era where we can truly say that the Persian empire became the crossroads of civilization. If one must go back to the very roots of "globalism" and a mercantile and transcultural approach to a worldly order, one cannot afford to leave out the Achaemenids.