Simplify the following text for a Grade 13 native English-speaking person.
Original: Observation 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 .
Simplified: Observation info for years before 1492 is completely unavailable because record keeping was non-existent in the pre-Columbian era , and any records that may have once existed have long since been lost .