How do I make players more comfortable in an unusual historical setting?

I run a lot of games/write systems set in specific historical/cultural contexts, because I like rpgs as a way to explore them and think they provide a great sense of place. However, I tend not to choose more well-known settings, like WWII Europe or Victorian England, because they’ve already been so thoroughly explored that they lose some of the uniqueness factor I’m interested in.

So far the people I’ve played/playtested them with have been enthusiastic about the ideas, but the games tend to start slow as they are hesitant to be creative because they don’t want to ‘be wrong’ about how things would work in that time and place. However, I’m not so much set on perfectly replicating, say, 19th century Hong Kong in a given game as I am interested in seeing the game evolve from an off-beat starting point.

Do people think the best solution to this is to separate the actual history from the game history (i.e. emphasize that this is an alternate universe and they can feel free to depart as much as they want to from the historical details) or to provide a lot of background information to ground them as much as possible in the time period so that they’re more comfortable there?