After the Treaty of Lancaster, Virginia and Pennsylvania colonial officials acted as if the Iroquois had sold them settlement rights to the Ohio Valley, but the Iroquois did not believe they had done so. In 1748, Pennsylvania sent Conrad Weiser to Logstown, a council and trade village on the Ohio River. Here he held council with chiefs representing 10 tribes, including the Delaware, Shawnee, and the six nations of the Iroquois. He arrived at a treaty of friendship between Pennsylvania and these tribes. Threatened by this development and the continued activity of British traders in the Ohio Valley, the French redoubled their diplomatic efforts. In addition, they began to build a string of forts to protect their interests, culminating in Fort Duquesne in 1754 at the confluence of the Allegheny and Monongahela rivers, forming the Ohio River. This is where present-day Pittsburgh, Pennsylvania later developed.