The Davien system is a planetary system in the United Empire of Earth (UEE). Discovered in SEY 2430, it was the system in which Humans first encountered intelligent extraterrestrial life: the Banu. People and businesses flocked to Davien after this, in spite of the thin atmosphere present in the system's only inhabitable planet, Cestulus (Davien II).
The 2546 Atrocity at Jata on Cestulus was a political flashpoint in the leadup to Ivar Messer I's ascension to Prime Citizen and ultimately Imperator.