Barid

[14] Under his successors, oversight of the barid was often entrusted to a prominent official or close associate of the caliph, such as the Barmakid Ja'far ibn Yahya or Itakh al-Turki.

[3][15] After the political fragmentation of the Abbasid Caliphate in the ninth and tenth centuries, the central diwan al-barid was overseen by the Buyids (945–1055),[16] but the organization seems to have declined during this period.

[20] Its messengers were capable of delivering missives throughout the empire with great efficiency, with reported travel speeds as fast as almost a hundred miles per day.

[22] To facilitate the swift delivery of its messages, the barid maintained an extensive network of relay stations, which housed fresh mounts, lodging and other resources for its couriers.

[3][24] Besides carrying correspondence, the barid was sometimes used to transport certain agents of the state, providing a form of fast travel for governors and other officials posted to the provinces.

[3][7] The Abbasid caliph al-Hadi (r. 785–786), for example, used the barid service to make the journey from Jurjan to the capital Baghdad after he had received news of his father's death.

The postmasters (ashab al-barid) of each district effectively doubled as informants for the central government, and regularly submitted reports to the capital of the state of their respective localities.

[28] Any events of significance, such as local trial proceedings,[29] fluctuations in prices of essential commodities,[30] or even unusual weather activity,[31] would be written about and sent to the director of the central diwan, who would summarize the information and present it to the caliph.