In the 1050s he compiled Synopsis historion (also known as A concise history of the world), which spanned the time from the biblical account of creation to his own day.
Kedrenos is one of the few sources that discuss Khazar polities in existence after the sack of Atil in 969 (see Georgius Tzul).
[1] One late manuscript of Synopsis historion preserves a poem (anonymous but thought to be by Kedrenos) that derives his family name from the place where he was born, a small village of Cedrus (or Cedrea) in the Anatolic Theme.
[2] Vestarches Georgios Kedrenos is in fact known from a number of 11th–12th-century seals found mostly in the Danube region, but also in Crimea.
[1][4][5][6] Furthermore, several roughly contemporary seals refer to another court official, a certain "John Cedrenus, protocuropalates and duke" who may have been a relative, perhaps, a brother or a cousin.