What did the development of Agriculture allow the Mississippian Indians to do

"The Mississippian Period lasted from approximately 800 to 1540 CE. It's called "Mississippian" because it began in the middle Mississippi River valley, between St. Louis and Vicksburg. However, there were other Mississippians as the culture spread across modern-day US. There were large Mississippian centers in Missouri, Ohio, and Oklahoma."

Explanation:

"The construction of large, truncated earthwork pyramid mounds, or platform mounds. Such mounds were usually square, rectangular, or occasionally circular. Structures (domestic houses, temples, burial buildings, or other) were usually constructed atop such mounds.

Maize-based agriculture. In most places, the development of Mississippian culture coincided with adoption of comparatively large-scale, intensive maize agriculture, which supported larger populations and craft specialization.

The adoption and use of riverine (or more rarely marine) shells as tempering agents in their shell tempered pottery.

Widespread trade networks extending as far west as the Rockies, north to the Great Lakes, south to the Gulf of Mexico, and east to the Atlantic Ocean."