Fort Ancient is a name for a Native American culture that flourished from 1000–1750 CE and predominantly inhabited land near the Ohio River valley in the areas of modern-day southern Ohio, northern Kentucky, southeastern Indiana and western West Virginia. Although a contemporary of the Mississippian culture, they are often considered a "sister culture" and distinguished from the Mississippian culture. While far from agreed upon, there is evidence to suggest that the Fort Ancient Culture were not the direct descendants of the Hopewellian Culture. It is suspected that the Fort Ancient Culture introduced maize agriculture to Ohio. The Fort Ancient Culture were most likely the builders of the Great Serpent Mound. Recent archeological study and carbon dating suggests that Alligator Mound in Granville also dates to the Fort Ancient era, rather than the assumed Hopewell era. It is believed that neither the Serpent or Alligator Mounds are burial locations, but rather served as ceremonial effigy sites.
The name of the culture originates from the Fort Ancient, Ohio archeological site. However, the Fort Ancient Site is now thought to have been built by Ohio Hopewellian people. It was likely occupied later by the succeeding Fort Ancient culture. The site is located on a hill above the Little Miami River, close to Lebanon, Ohio. Despite its name, most archaeologists do not believe that Fort Ancient was used primarily as a fortress by either the Ohio Hopewell culture or the Fort Ancient culture; it was more likely to have been a ceremonial location.
Starting in about 1000 CE, terminal Late Woodland groups in the Middle Ohio Valley adopted maize agriculture. They began settling in small, year-round nuclear family households and settlements of no more than 40 to 50 individuals. These small scattered settlements, located along terraces that overlooked rivers and sometimes on flood plains, would be occupied for short periods before the groups moved on to new locations.
By 1200, the small villages began to coalesce into larger settlements of up to 300 people.