Complex sentence: The original founders of Burlington consisted entirely of settlers from New England, and inherited "Yankee" culture, that is, they were descended from the English Puritans who settled New England in the 1600s.
Split into simpler sentences: The original founders of Burlington consisted entirely of settlers from New England. These people were "Yankee's", that is to say they were descended from the English Puritans who settled New England in the 1600s.