OTL, there were large areas of the Roman Empire that could have supported Latin settlement, or developed their own Romance languages, but didn't. This includes broad areas like:
- England
- Northumbria/South Scotland/Between the Hadriatic and Antionne walls
- Vasconia
- Egypt
- Anatolia
- The Levant
- Mesopotamia
- Other areas in Europe where Latin was widespread but died out
- Greece