You can tell a lot about a state from its transport system, and our chariot tells us a great deal about imperial Persia. … Public order was so secure that people could travel long distances without armed guards. And they could travel fast. With its horses specially bred for strength and speed, and with its large, steadying wheels, this chariot was the Ferrari or Porsche of its time. Broad dirt roads were kept wheel-worthy in all weathers, and there were frequent staging posts. Commands from the centre could be transmitted at speed across the whole territory, thanks to an entirely reliable royal postal service that used horsemen, runners and express messengers.

Neil MacGregor, A History of the World in 1…, loc. 443