British colonists. In the 17th century, most were of English origins, but in the 18th century, large groups of Scots and Ulster-Scots (later called the Scots-Irish) settled in Appalachia and the Piedmont. These people engaged in warfare, trade, and cultural exchanges with the Native Americans already in the region (such as the Creek Indians and Cherokees). After 1700, large groups of African slaves were brought in to work on the large plantations that dominated export agriculture, growing tobacco, rice, and indigo. Cotton became dominant after 1800. The explosion of cotton cultivation[4] made the "peculiar institution" of slavery an integral part of the South's early 19th century economy. The oldest university in the South, the College of William and Mary, was founded in Virginia; it pioneered in the teaching of political economy and educated future U.S. Presidents Jefferson, Monroe and Tyler, all from Virginia. Indeed, the entire region dominated politics in the First Party System era: for example, four of the first five Presidents— Washington, Jefferson, Madison, and Monroe—were from Virginia. Two major political issues that festered in the first half of the 19th century caused political alignment along sectional lines, strengthened the identities of North and South as distinct regions with certain strongly opposed interests and fed the arguments over states' rights that culminated in secession and the Civil War. One of these issues concerned the protective tariffs enacted to assist the growth of the manufacturing sector, primarily in the North. ]