Sentence:  Old attitudes are held more tenaciously in the Tidewater than the Piedmont ; so that a line running down the length of the South marking the upper limits of tidewater would roughly divide the Old South from the new , but with , of course , important <WSD>minority</WSD> enclaves . 
Meaning of the word marked with <WSD> tags:  a group of people who differ racially or politically from a larger group of which it is a part