The Hopewell civilization refers to a culture shared by native Americans tribes from about 200 BC to 400 AD that spanned a region from the eastern coast to the Rocky Mountains, and from the Great Lakes to the Gulf of Mexico. The fairly rapid decline of this culture has been a mystery for many years. A group of researchers from the University of Cincinnati found evidence of a Tunguska-like airburst that struck sometime between 252 and 383 AD and affected an area of 9200 square miles (24,000 sq km). That time range coincides with a period when 69 near-Earth comets were observed and documented by Chinese astronomers, and many Native American tribes include some sort of devastating event from the skies in their oral histories.
Their results are presented in a Scientifc Reports paper:
Near-Earth comets have been increasing through time (up to 2 per year) and those with an orbital period of ~10,000 years may remain within a planetary system between 5,000 and 15,000 years. Thus, we expect to find more examples of such events in the archaeological record.
Tankersley, K.B., Meyers, S.D., Meyers, S.A. et al. The Hopewell airburst event, 1699–1567 years ago (252–383 CE). [open] Sci Rep 12, 1706 (2022). DOI: 10.1038/s41598-022-05758-y