Final answer:
The Middle Woodland culture, especially the Hopewell tradition, constructed complicated burial mounds filled with artifacts during AD 1-500. These mounds are indicative of complex social structures and extensive trade networks within the Eastern Woodlands region.
Step-by-step explanation:
The group that constructed complicated burial mounds filled with artifacts during the period AD 1-500 was the Middle Woodland culture, particularly embodied by the Hopewell tradition. The Hopewell societies are renowned for their continuation of mound-building, which was initiated by the earlier Adena culture around 1000 BCE. These cultures were located in the Eastern Woodlands region of what is now the United States.One of the main characteristics of the Hopewell societies was their extensive trade system, known as the "Hopewell exchange system," which connected many parts of the North American continent. Rich and varied grave goods found within the burial mounds, such as shells from distant regions, obsidian, and mica, are testaments to this expansive trade network. The mounds served as burial sites and possibly played roles in various ceremonial purposes.The artifacts found within these mounds indicate a society with differentiated social classes and a reduction in egalitarianism. This is also supported by the presence of exotic trade items, which point to the rising complexity and sophistication of these cultures within the Eastern Woodlands.