THE largest area of unexplored country east of the Mississippi in the early years of the eighteenth century was the upper Ohio Valley, including western Pennsylvania. The English had occupied the Atlantic coast plain, the Spanish the Floridas, and the French the St. Lawrence and Mississippi valleys and the upper Great Lakes region, but as yet no establishments had been made by white men in the great Appalachian Plateau that stretched westward from the mountains to the lake and prairie plains. The reasons for the delay in the exploration of this region are fairly obvious. The English on the coast were shut off from it by the broad belt of the Appalachian Mountains, and the French were barred from the natural entrance into the region through Lake Erie by the opposition of the powerful Iroquois. More effective, however, than either of these obstacles was the fact that the region had been stripped of its Indian inhabitants by the Iroquois conquests and so lacked attractions for traders or missionaries, the usual forerunners of the white advance.
Although the Appalachian Plateau was unoccupied it was not unclaimed by Europeans. The English, basing their claims on the explorations of the Cabots along the Atlantic coast, expressed them in their sea-to-sea charters and in the grant of 1681 to William Penn extending five degrees west of the Delaware River. About a year after the chartering of Pennsylvania, La Salle, by a ceremony at the mouth of the Mississippi, took formal possession in the name of the king of France of all the land drained by that river and its tributaries. Years before this, however, the French in the St. Lawrence Valley and the Dutch on the Hudson had learned of the upper Ohio country from the Indians. In 1669 La Salle and two Sulpicians, Dollier de Casson and Galine'e, set out from Montreal with twenty-one men, intending to go to the West by way of the Ohio River. They made their way