In c. 1750, over half of the population of the thirteen colonies was still of English descent, but significant minorities were beginning to establish themselves. The largest of these was African, predominantly slaves, and overwhelmingly concentrated in the plantations of Virginia and the southern colonies. The Scots-Irish, mainly Presbyterians from Ulster, gravitated to the western frontiers, where the land was free, and colonial oversight lax. They became the dominant population throughout Virginia and the west Carolinas. Highland Scots, who came in increasing numbers after the crushing of the 1745 rebellion, clustered in Gaelic-speaking enclaves along the rivers of North Carolina and Georgia. Germans, including sects like the Mennonites and Moravians, concentrated where religious tolerance was promulgated, in Pennsylvania, upstate New York and Georgia. The Jewish population, less than 1 per cent of the total, developed significant enclaves in New York (from the Dutch period on) and in Savannah, Georgia.