The people produced pipes, depicting forest animals and birds, which have been found from lake superior to the gulf of mexico.

Answer;
The Hope well people produced pipes, depicting forest, animals and birds, which have been found from Lake Superior to the gulf of Mexico. 

Explanation; 
The Hopewell people built massive earthworks and numerous mounds while crafting fine works of art whose meaning often eludes modern archaeologists. 
They used distinctive stone pipes, often with effiges on them.