When Europeans first reached Florida, the area around Tampa Bay and all of the watershed of the Hillsborough River was occupied by people of the Safety Harbor culture. Two chiefdoms of the Safety Harbor culture, Mocoso and Pohoy, were adjacent to where the Hillsborough River entered Tampa Bay. Hernando de Soto landed on the south side of Tampa Bay in 1539 and passed through Mocoso on his way north. By the early 18th century the people of the Safety Harbor culture, through disease and slavery, are nearly exterminated.