The Olmec flourished during the Formative (or Preclassic) period of Mesoamerican chronology, dating from 1200 B.C.E. to about 400 B.C.E., and are believed to have been the progenitor civilization of later Mesoamerican civilizations. However their culture disappeared for reasons unknown. Still, much of their culture remains and the Olmec are credited (at least speculatively) with many innovations in Mesoamerica, including writing, the calendar using zero, and the Mesoamerican ballgame prevalent in the region. Their place in human history remains significant and not to be forgotten, most obviously seen in the colossal stone heads, examples of which have been found around the area they inhabited.