It is most likely to have been written in Constantinople about 551AD. It is a summary of the now lost Gothic History of Cassiodorus. How much of this work can be attributed to Jordanes, and how much should be considered Cassiodorus' is disputed.
This work claims to have the Gothic "Folk songs" - the "Carmina Prisca" (Latin) as a prime source. Recent scholarship regards this as highly questionable. The main purpose of the original work (Cassiodorus's) was to give the gothic ruling class a glorius past - to match the past of the senatorial families of Italy.