To ensure the control and development of his immense empire, the persian Achaemenid King Darius the Great connected his cities by means of a network of stone-paved roads , along which caravans could journey safely and comfortably, in the knowledge that at every twenty-four kilometers was a military post and a caravanserai.

The swift post riders on the famous Royal Road covered a distance of 2.700 kilometers from Susa, the persian capital to Sardis, in Lydia (current Turkey) in seven to ten days, an unheard speed of those times.

Herodotus, the greek historian, who traveled on the entire Royal Road, wrote: ” Neither snow, nor rain, nor frost, nor darkness could hinder the swift couriers of the post of Darius.”

The quality of the Royal Road was such that it still remained in use during the roman era and as part of the Silk Road to East Asia.