Answer:
the arrival of Europeans
the creation of European settlements
Step-by-step explanation:
Mississippi is a state in the Southern area in the US. The area was known for its great landscape and production of ornaments due to its degree of civilization of the Native Americans.
The event ultimately that brought about the decline of Mississippian civilizations includes the arrival of Europeans and the creation of European settlements. The immigrants weren’t as civilized as the native people which brought to a decrease in the civilization of the state.