I always think of history as kind of a tapestry, and filling in pieces (neighboring states, for example) can be reasonably informative.

If I were working backwards, since you're into podcasts, The History of Rome is obviously quite good, and The History of England essentially picks up the historical narrative with the Anglo-Saxon states prior to the Norman invasion. Having a good, digestible background (through these) makes the "missing middle" easier to fit in. There are very few easy/readable histories of it, but there are good histories of the Merovingians, for example, which can inform a lot about the neighboring region.