I recently (19th of May) had to reinstall Linux. I thought I had everything backed up, but apparently I forgot to backup my Firefox profile. I'd lost a few years of bookmarks and my current session, but c'est la vie, back up better next time. I *did* have Firefox Sync, but after checking the support forums saying Sync is not a backup tool, I'd lost hope. I *did* have an older device, so I booted that up to get up to about 18 months ago. But when I did so, I was able to get history and bookmarks up to the 14th of April (this year), despite not booting that device since long before then. I'm not looking a gift horse in the mouth, but where did this come from, and could the other 4 weeks be hiding there?