 Stone tools, the oldest evidence of human occupation in Costa Rica, are associated with the arrival of various groups of hunter-gatherers about 10,000 to 7,000 years BCE in the Turrialba Valley.The presence of Clovis culture type spearheads and arrows from South America opens the possibility that, in this area, two different cultures coexisted.Agriculture became evident in the populations that lived in Costa Rica about 5,000 years ago.