John Skylitzes in the context of Byzantine Greek language

The Madrid Skylitzes is a 12th-century illuminated manuscript version of the Synopsis of Histories (Greek: Σύνοψις Ἱστοριῶν) by John Skylitzes, which covers the reigns of the Byzantine emperors from the death of Nicephorus I in 811 to the deposition of Michael VI in 1057. The manuscript was produced at the Norman court of Palermo in Sicily (although there is some debate on whether the main body was made in Palermo or Constantinople) and is now housed in the Biblioteca Nacional de España in Madrid. It remains the only preserved Greek-language illustrated chronicle from the Byzantine period. The chronicle includes 574 miniatures detailing depictions of everyday life in the Byzantine Empire such as boats, literary practices, sieges, and ceremonies, in "both purely Byzantine and Western styles while also reflecting Islamic elements".

The Battle of Spercheios (Bulgarian: Битка при Сперхей, Greek: Μάχη του Σπερχειού) took place in 997 AD, on the shores of the Spercheios river near the city of Lamia in central Greece. It was fought between a Bulgarian army led by Tsar Samuil, which in the previous year had penetrated south into Greece, and a Byzantine army under the command of General Nikephoros Ouranos. The Byzantine victory virtually destroyed the Bulgarian army, and ended its raids in the southern Balkans and Greece. The major historical source on the battle comes from Greek historian John Skylitzes whose Synopsis of Histories (Σύνοψις Ἱστοριῶν) contains a biography of the then-reigning Byzantine emperor, Basil II.

The Varangian Guard (Greek: Τάγμα τῶν Βαράγγων, romanized: Tágma tōn Varángōn) was an elite unit of the Byzantine army from the 10th to the 14th century who served as personal bodyguards to the Byzantine emperors. The Varangian Guard was known for being primarily composed of recruits from Northern Europe, including mainly Norsemen from Scandinavia but also Anglo-Saxons from England. The recruitment of distant fighters from outside Byzantium to serve as the emperor's personal guard was pursued as a deliberate policy, as they lacked local political loyalties and could be counted upon to suppress revolts by disloyal Byzantine factions.

The Rus' provided the earliest members of the Varangian Guard. They were in Byzantine service from as early as 874. The Guard was first formally constituted under Emperor Basil II in 988, following the Christianization of Kievan Rus' by Vladimir I of Kiev. Vladimir, who had recently taken control of Kiev with an army of Varangian warriors, sent 6,000 men to Basil as part of a military assistance agreement. Basil's distrust of the native Byzantine guardsmen, whose loyalties often shifted with fatal consequences, as well as the proven loyalty of the Varangians, many of whom had previously served in Byzantium, led the Emperor to employ them as his personal guardsmen.