One of the first frontier regions of the United States, the area encompassed roughly all of present-day Ohio, northwestern West Virginia, Western Pennsylvania, and eastern Indiana. Historians believe that the issue of Anglo-American settlement in the region was a primary cause of the French and Indian War and a contributing factor to the American Revolutionary War.
After the Revolution and the resolution of state claims to the territory, the Northwest Ordinance of 1787 established the boundaries of the Northwest Territory, which was larger than the Ohio Country. The territory included all the land of the United States west of Pennsylvania and northwest of the Ohio River. It covered all of the modern states of Ohio, Indiana, Illinois, Michigan, Wisconsin, and the northeastern part of Minnesota. The area covered more than 260,000 square miles (670,000 km2).
In the 17th century, the area north of the Ohio River had been occupied by the Algonquian-speaking Shawnee and some Siouan language-speaking tribes. Around 1660, during a conflict known as the Beaver Wars, the Iroquois seized control of the Ohio Country, driving out the Shawnee and Siouans, such as the Omaha and Ponca, who settled further northwest and west. The Iroquois conquered and absorbed the Erie, who also spoke an Iroquoian language. The Ohio Country remained largely uninhabited for decades, and was used primarily as a hunting ground by the Iroquois.
In the 1720s, a number of Native American groups began to migrate to the Ohio Country from the East, driven by pressure from encroaching colonists. By 1724, Delaware Indians had established the village of Kittanning on the Allegheny River in present-day western Pennsylvania. With them came those Shawnee who had historically settled in the east. Other bands of the scattered Shawnee tribe began to return to the Ohio Country in the decades that followed. A number of Seneca and other Iroquois also migrated to the Ohio Country, moving away from the French and British imperial rivalries south of Lake Ontario. The Seneca were the westernmost of the Iroquois nations based in New York.
In the late 1740s and the second half of the 18th century, the British angled for control of the territory. In 1749, the British Crown, via the colonial government of Virginia, granted the Ohio Company a great deal of this territory on the condition that it be settled by British colonists.