The other major candidate is the Olmec heartland, across the Isthmus of Tehuantepec along the Gulf Coast. The Aztecs referred to their Postclassic contemporaries who then inhabited the region as the Olmeca (i.e. rubber people) since the region was strongly identified with latex production. The earliest-known rubber balls in the world come from the sacrificial bog at El Manatí, an early Olmec-associated site located in the hinterland of the Coatzacoalcos River drainage system. Villagers, and subsequently archaeologists, have recovered a dozen balls ranging in diameter from 10 to 22 cm from the freshwater spring there. Five of these balls have been dated to the earliest-known occupational phase for the site, approximately 1700-1600 BCE. These rubber balls were found with other ritual offerings buried at the site, indicating that even at this early date ōllamaliztli had religious and ritual connotations. A stone yoke of the type frequently associated with Mesoamerican ballcourts was also reported to have been found by local villagers at the site, leaving open the distinct possibility that these rubber balls were related to the ritual ballgame, and not simply an independent form of sacrificial offering.