From StarfinderWiki

The Gap is a recent phenomenon affecting all the memories and records across the multiverse. All memories and records of the planet Golarion were removed from all of the multiverse's inhabitants along with all memories of an indeterminate number of years. Even the deities are silent on the subject, vaguely referring to the safety of the lost planet of Golarion. No members of any species remembers what happened during the unknown number of years covered by the Gap.[1][2][3]

Length of the Gap

Very little is known about what happened during the Gap, or even how long it lasted. Judging from carbon dating and astrochronology, it seemed to have lasted several millennia, although the exact end dates vary by location. Some planets record that it ended 310 years ago, while on others it seems to have ended only 275 before the present day.Cite error: Invalid <ref> tag; invalid names, e.g. too many