Pottery recovered from beneath the mounds was found to be proto - Natchezan .
Was instrumental in defining the protohistoric Foster Phase ( 1350 to 1500 CE ) of the Plaquemine culture chronology .
Pottery recovered from beneath the mounds was found to be proto - Natchezan and was instrumental in defining the protohistoric Foster Phase ( 1350 to 1500 CE ) of the Plaquemine culture chronology .