Final answer:
The conical burial mounds with exotic grave goods in the Ohio River Valley are attributed to the Adena culture, which was part of a series of mound-building societies and flourished from the first century CE to 400 CE.
Step-by-step explanation:
The conical burial mounds in the Ohio River Valley that contain exotic grave goods belong to the Adena culture. The Adena culture, along with the subsequent Hopewell culture, were part of a series of mound-building societies in this region that constructed burial mounds and other types of earthworks. These societies flourished during different periods, with the Adena culture reaching its peak from the first century CE to 400 CE, and the Hopewell culture continuing this tradition onwards. The Adena culture is particularly well-known for conical burial mounds where the deceased were interred with elaborate grave goods like copper bracelets, beads, and cups, indicating a socially stratified society. These burial artifacts, alongside mounds like the Great Serpent Mound, provide a glimpse into the rich spiritual and ceremonial practices of these early indigenous cultures of North America.