Persian couriers
In Ancient Greek, Persian courier was called ἄγγαρος (ángaros, “Persian mounted courier”), whence Latin angarius, which is probably from an East Asian language (e.g., Sanskrit अजिरा (ajirā, “agile, swift”)). The word "angel" (ἄγγελος) is probably loaned from and related to Greek ἄγγαρος.