Simplify the following text for a Grade 9 native English-speaking person.
Original: The Olmec were the first civilization in the ancient area known as Mesoamerica . Because they were the first civilization , many later Mesoamerican civilizations used and repeated Olmec features and characteristics .
Simplified: It is not known what name the ancient Olmec used for themselves ; some later Mesoamerican accounts seem to refer to the ancient Olmec as `` Tamoanchan '' .