Wikipedia
The Piankeshaw (or Piankashaw) Indians were Native Americans and members of the Miami Indians who lived apart from the rest of the Miami nation. They lived in an area that now includes western Indiana and Ohio, and were closely allied with the Wea Indians. Piankeshaw villages have been reported along the White River in central Indiana, and along the Vermilion River in Illinois, near Ouiatenon. The Piankashaw were living along the Vermilion river in 1743.
The Piankeshaw are usually regarded as being "friendly" towards European settlers. They intermarried with French traders and were treated as equals by residents of New France in the Illinois Country. A principal Piankeshaw village was established on the Wabash River near what became Vincennes. In fact, some have suggested that the land around the Grand Rapids Hotel that existed in the 1920s was part of a Piankeshaw Summer campground. Like their French neighbors, the Piankeshaw generally sided with the Americans during the American Revolution.
Although part of the Wabash Confederacy, the Piankeshaw nation took no part in the Northwest Indian War that followed the American Revolution. However, Piankeshaw suffered retaliation from Americans for attacks made by other native tribes. President George Washington issued a proclamation forbidding harm to the Piankeshaw.
During the late 18th century, the Piankeshaw population began to decline. Many of the Piankeshaw simply left and joined other Miami tribes. After the Americans and French suffered setbacks in the Revolution, notably the disastrous LaBalme expedition, some Piankeshaw joined tribes aligned with the British. At that time, in the West, the British looked as if they would be the victors.
Others left during the economic depression caused by a depreciated United States currency and stagnated fur trade (due to unrest in the Northwest Indian Wars). The Piankeshaw suffered especially when 1781 brought a severe Winter followed by a Summer drought.
Despite overall good relations with the new United States, some Piankeshaw resented the new settlers encroaching on their territory. They joined with other tribes in attacking American settlers. This led to increasing tension at Vincennes, which peaked after an attack on the Embarras River by Kentucky resident Patrick Brown in August 1788.
A large exodus of Piankeshaw left Vincennes and moved to Terre Haute, where they joined the Wea, or moved to Kaskaskia, Illinois. By 1818, the Piankeshaw chief Chekommia signed a treaty selling rights to much of their land to the United States. There were not enough tribal members remaining to use it.