Over a period of some forty years, 380/990–421/1030, the Fatimids in Egypt exchanged embassies with their Zirid viceroys in Ifrīqiya after these had been recognized as a hereditary dynasty, and to a lesser extent with their Kalbid deputies in Sicily. Sijillāt or official letters of the Fatimid chancery, accompanied by sumptuous presents, invested the Zirids with their authority and favoured them with important announcements, while the Zirids replied in kind. The embassies were ostentatiously welcomed by the Zirids as proof of their legitimacy, while serving to maintain the connection with Cairo on which the Fatimids were similarly dependent for the sake of their imperial standing in the world. The importance of that connection to both dynasties was shown in the 440s/1050s, when it was broken by the Zirids and restored by a Fatimid intervention, celebrated in a fresh series of sijillāt. With their emphasis on the style as much as the substance of the messages, the exchanges are excellent illustrations of mediaeval diplomatic correspondence as described by John Wansbrough in Lingua Franca in the Mediterranean.