Babylon was one of several great Sumerian city-states in Mesopotamia, controlling its hinterland by means of a sophisticated irrigation system. Marduk, its patron god, defined the Pattern for all human cities when Babylon was founded. The Children of Gaia attempted to influence civilization in this region, teaching them to live in harmony with Gaia, but had little success.
Babylon was rife with demons, thanks to the priests of Etemenanki, who disguised their Infernalist practices as a form of worship of Marduk. They used ritual sex to open a portal to the Void, and later Malfeas itself, inviting in all manner of dangerous and destructive spirits. Marduk himself lead a crusade against the infernalists, and eventually defeated them, though Babylon itself fell from glory soon after.
Babylon had a long tradition of magic meant to fight demons, and in the Final Nights many mages (particularly the Order of Hermes) developed a renewed interest in these spells and whether they could be applied to fighting the Nephandi. Babylonian astrologers knew how to decipher the future from the stars, intercepting communications between the Pure Ones and their Infernal followers. The Enuma Anu Enlil, a lengthy list of prophecies, includes an entire section devoted to the Anunnaku.