1820 in the political sense, "local attachment as opposed to national unity," from provincial + -ism. Meaning "a certain narrowness of localism of thought or interest; lack of polish or enlightenment," reflecting manners or modes of a certain province or of provinces generally (as opposed to the big city or the capital) is by 1836. Sense of "a local word or usage or expression" is from 1770.
To me provincialism stood, and stands, for the sum-total of all false values; it is the estimation of people for what they have, or pretend to have, and not for what they are. Artificial classifications, rigid lines of demarkation that bear no relation whatsoever to intrinsic merit, seem to belong to its very essence, while contempt for intelligence, suspicion and fear of independent thought, appear to be necessary passports to provincial popularity. [Vera Brittain, "Testament of Youth"]