Answer:
The mound builders built mounds at Cahokia.
Step-by-step explanation:
Research made by historians shows that the mound builders are the ancient people who built mound at Cahokia city. This was the large man made structure built by mound builders for the beautification of this city. At the beginning i. e. in 7th century, there are about 1000 people living in this city but the population exceeds to 10000 people in 11th century.