Small correction: その村にどうな人が住んでいたかが書いてある。--> どんな
It's (…住んでいたか) + (が) + (書いてある)
Let's think like this:
(something) が + 書いてある = Someone wrote something on the paper / there are something written on the paper /
It says ... on the paper / the paper said ... .
*I think, in English, there are several ways of translation and in general, "it said ..." is used for articles/ informations.
か of 住んでいたか is the sentence ending particle for question (どんな人が住んでいましたか) and in this case, it's used in the indirect speech. So, this かが is the sentence ending particle + が.
I hope my explanation could help you...