Byzantine diplomacy

[1] After the fall of the Western Roman Empire, the key challenge to the Eastern Roman Empire was to maintain a set of relations between itself and its sundry neighbors, including the Persians, Georgians, Iberians, the Germanic peoples, the Bulgars, the Slavs, the Armenians, the Huns, the Avars, the Franks, the Lombards, and the Arabs, that embodied and so maintained its imperial status.

With a regular army of 120,000-140,000 men after the losses of the seventh century,[2] the empire's security depended on activist diplomacy.

Byzantium's "Bureau of Barbarians" was the first foreign intelligence agency, gathering information on the empire’s rivals from every imaginable source.

[3] While on the surface a protocol office—its main duty was to ensure foreign envoys were properly cared for and received sufficient state funds for their maintenance, and it kept all the official translators—it clearly had a security function as well.

A member of other royal houses would routinely be requested to stay in Constantinople, not only as a potential hostage, but also as a useful pawn in case political conditions where he came from changed.

[7] When Liutprand of Cremona was sent as an ambassador to the Byzantine capital, he was overwhelmed by the imperial residence, the luxurious meals, and acrobatic entertainment.

Special care was taken to stimulate as many of the senses in as high degree as possible: brightly lit things to see, terrifying sounds, tasty food; even the diplomatic set-piece of having barbarians standing around the throne wearing their native gear.