Smithsonian Magazine has a complete article on this treaty and how it balanced the power with the newly formed United States.
From the Smithsonian Blog, Smithsonian Voices, Museum of the American Indian; 2018 May 21: A Brief Balance of Power—The 1778 Treaty with the Delaware Nation:
“On September 17, 1778, the newly formed United States Continental Congress dispatched a treaty commission to the confluence of the Monongahela and Allegheny rivers to negotiate America’s first treaty of peace with an American Indian tribe.
Three leaders—named in the treaty as “Capt. White Eyes, Capt. John Kill Buck, Junior, and Capt. Pipe, Deputies and Chief Men of the Delaware Nation”—represented the Lenape (Delaware) people.
During colonial times, Lenape communities had been compelled to move west from their historic home along the Delaware and lower Hudson River watersheds to lands between modern-day Pittsburgh and Detroit. General Andrew Thomas and his brother Lewis served as commissioners on behalf of the United States. Eleven other Americans witnessed what would become known as the Treaty of Fort Pitt.” ~ Dennis Zotigh
The Delaware Indians came to Indiana and settled along the White River as early as 1795.
National Museum of the American Indian
Smithsonian Voices Blog
Full Article: A Brief Balance of Power—The 1778 Treaty with the Delaware Nation