Northwestern North America was pretty snowy and cold. To adapt to this freezing environment, tribes like Eskimo lived in igloos and ate lots of fish. They also had thick waterproof clothes to combat snow.
If we want to go a little bit more south to an area like Washington state, then it gets a little warmer. Tribes like the Chinook also liked to eat a lot of seafood, but they also lived in wood houses.
The geographic factor was actually their location.
The Romans were implementing the Latin language as the language of the administration for both, practical reasons and also assimilation of the native population they have managed to conquer.
By making the local chieftains learn, speak, and use the Latin language, the Romans played very well tactically, because in this way the leaders of the tribes were slowly becoming assimilated into the Roman culture, and once the local leaders are assimilated it has a chain reaction and the people that are under their guidance are starting to assimilate as well.
