So, there is a specific sort of ahistory which you can see in most D&D settings (and which many more thought out setting deliberately avoid) which is to make it technologically historical, but conceptually contemporary.
That is to say, people are running around with swords and horses, but they also have modern ideas of things like refridgeration, urban planning, hygiene, politics and so on. That is to say, it's *comfortable* for a modern (american) person to think about.