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 minority <WSD>enclaves</WSD> . 
Meaning of the word marked with <WSD> tags:  an enclosed territory that is culturally distinct from the foreign territory that surrounds it