Biblical Pseudepigrapha
Tartarus is only known in Hellenistic Jewish literature from the Greek text of 1 Enoch, dated to 400–200 BC. This states that God placed the archangel Uriel "in charge of the world and of Tartarus" (20:2). Tartarus is generally understood to be the place where 200 fallen Watchers (angels) are imprisoned.
Read more about this topic: Tartarus