Diwan al-barid (English spelling)

...The first caliph of the Umayyad dynasty, Muawiyah I (reigned 661-680), followed the relay system of Sassanid Persia and the Byzantine Empire, and the fifth caliph, Abd al-Malik (reigned 685-705), who put down the second civil war (683-692), institutionalized it and made it the key to governing the empire. During the Abbasid period, the Barid became an even more important government institution, and the second caliph, Mansur (reigned 754-775), established a relay office in Baghdad, as well as relay offices in the provincial capitals, each of which was staffed with trusted subordinates. They were responsible not only for transmitting official documents, but also for writing reports on the activities of local governors and judges, daily price fluctuations, etc.

*Some of the terminology explanations that mention "dīwan al-barīd" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…ウマイヤ朝の初代カリフ，ムアーウィヤ1世(在位661‐680)がササン朝ペルシアやビザンティン帝国の駅伝制を踏襲し，第2次内乱(683‐692)を平定した第5代カリフ，アブド･アルマリク(在位685‐705)はこれを組織化して帝国統治のかなめとした。アッバース朝時代になるとバリードはさらに重要な政府機関となり，第2代カリフ，マンスール(在位754‐775)はバグダードに駅伝庁dīwān al‐barīdを設置するとともに，地方の主都にも駅伝局を置いてそれぞれに腹心の部下を配した。彼らは公文書の伝達ばかりでなく，地方総督や裁判官の活動のようす，毎日の物価の動きなどを書き送る義務を負っていた。…

※「dīwān al-barīd」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報