Data for years before 1492 is completely unavailable because record keeping was virtually non-existent in the pre-Columbian era, and any records that may have once existed have long since been lost. However, studies of sediment deposits in Florida have revealed that a very strong series of hurricanes struck the region thousands of years ago. Even data from the early years of the Columbian era is suspect and incomplete because the distinction between a hurricane and an extratropical system was not drawn by Renaissance scientists and sailors and because European exploration and colonization of the regions affected by hurricanes did not begin in earnest until the mid-16th century.