Definition: Rewrite each original sentence in order to make it easier to understand by non-native speakers of English. You can do so by replacing complex words with simpler synonyms (i.e. paraphrasing), deleting unimportant information (i.e. compression), and/or splitting a long complex sentence into several simpler ones. The final simplified sentences need to be grammatical, fluent, and retain the main ideas of their original counterparts without altering their meanings.
Input: Atlantic hurricane seasons Pre-1600 1600s / 10s 1620s / 30s 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.

Observation data for Hurricanes for years before 1492 is completely unavailable because record keeping was almost non-existent and lost.