I would use commas in both, the first because it is a fronted sentence adverbial (you wouldn't need the comma if the phrase came at the end of the sentence), and the second because its omission mis-references 'however'. After *** fell in 1937 , there were many wealthy people in YYY. However, in most of the relevant texts , it was the people from that district who got the most benefits from the current programs.
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