> These all reflect essentially distinct cultural communities in constant trade and travel for hundreds and hundreds of years Most people didn't leave their lo

> These all reflect essentially distinct cultural communities in constant trade and travel for hundreds and hundreds of years Most people didn't leave their local area, the need for a unified language was extremely limited compared to modern society. Dialects developed because interaction was so low, so you could easily hear which part everyone came from, today all of that is evening out over time. Go a few hundred miles and people use different words even if it is the same language and people would have a hard time understanding each other.