Information, like people and goods, could be moved from one part of the Empire to another only through a network of roads, and the importance attached by the Assyrian administration to effective communication can be gauged by the way it developed the road system. Added to the old network of commercial and local roads was a highway called "the king's road" (hūl šarri), traversing the Empire from East to West and from North to South.
Little physical evidence of it remains, but its course can be largely reconstructed from numerous references in contemporary documents.[[5]] Both its function (see below) and scattered textual references imply that it was a carefully maintained highway specifically built for rapid and safe transit traffic.
At regular intervals (mardētu "stage", lit. "day's march", a distance of c. 30 km) on this highway were garrisoned road stations (bēt mardēti) serving as resting places for the royal army and as relay points for imperial messengers. Each station was to keep in readiness a fresh team (urû) of mules[[6]] plus a chariot and a driver, which the messenger passing through would exchange for his tired team, thus being able to continue the journey at full speed and without interruption. The technical term for this service was kalliu, a word literally meaning "reserved/held back" and hence referring primarily to the relay team, but mostly used in the extended sense of "express service" (in adverbial usage "by express, post-haste").[[7]]
By the relay system, military and administrative messages could be rushed from the capital to any part of the empire and vice versa in a matter of a few days. The service was, of course, only available for important government business and using it generally required royal authorisation in writing; its maintenance was the responsibility of the provincial governors.[[8]]
5 See K. Kessler, Untersuchungen zur historischen Topographie Nordmesopotamiens (Wiesbaden 1980), 183-236. A mere glance at the article harrānu in CAD H 106ff will suffice to make it clear that "the king's road" in the sense described here was a creation of the Neo-Assyrian Empire.
6 Mules were preferred to horses as relay animals because of their superior qualities as long-distance runners.
7 The relay system seems to have already existed (at least in a limited form) in second-millennium Babylonia, see the evidence put together in CAD K 83f under kallû. However, it was certainly developed into the system described here (and later taken over by the Persians and the Romans) only under the Neo-Assyrian empire.
8 See, e.g., ABL 408 and NL 62.
Simo Parpola
Simo Parpola, 'The King's Road and the Relay System', The Correspondence of Sargon II, Part I: Letters from Assyria and the West, SAA 1. Original publication: Helsinki, Helsinki University Press, 1987; online contents: SAAo/SAA01 Project, a sub-project of MOCCI, 2020 [http://oracc.org/saao/saa01/administrativecommunication/kingsroad/]