The Ohio Country (sometimes called the Ohio Territory) was the name used in the 18th century for the regions of North America west of the Appalachian Mountains and in the region of the upper Ohio River south of Lake Erie. One of the first frontier regions of the United States, the area encompassed roughly the present-day states of Ohio, eastern Indiana, western Pennsylvania, and northwestern West Virginia. The issue of settlement in the region is considered by historians to have been a primary cause of the French and Indian War and a contributing factor to the American Revolutionary War.