This book is about the prehistoric mounds found in Ohio and the debate surrounding their origin. Cyrus Thomas, an archaeologist, challenges the popular theory of his time that a separate, more advanced race built the mounds before the Native Americans arrived. Through detailed examination of the mounds, their artifacts, and historical records, Thomas argues that the mounds were constructed by the ancestors of the Native American tribes living in the region at the time of European contact. The book provides a comprehensive overview of the mounds, their construction, and the cultural practices of the people who built them.