Complex sentence: It preserved works such as Tacitus' "Annales", Ammianus Marcellinus' "Res gestae", and the Codex Fuldensis which has the reputation of serving as the cradle of Old High German literature.
Split into simpler sentences: It preserved works such as Tacitus' "Annales", Ammianus Marcellinus' "Res gestae", and the Codex Fuldensis. The has the reputation of serving as the cradle of Old High German literature.