Complex sentence: Over the Archaic period of 8000 to 2000 BC, nuts, berries, fish and shellfish became part of the diet, and trade between the coastal plain and the piedmont developed.
Split into simpler sentences: Over the Archaic period of 8000 to 2000 BC, the people gathered nuts, berries, fish and shellfish as part of their diets. Trade between the coastal plain and the piedmont developed.