Seriously, though. There are a lot of open questions on dating old and middle kingdom events. The issue is not that there is no good chronology, it's rather that there are multiple reasonable and established chronologies that conflict. Entire careers have been made on basically arguing about dates.
We can date important events after the 8th century BCE pretty well for the entire Levant, thanks to the hard work of Babylonian royal astronomers who around that time started systematically recording all celestial events on clay tablets, on which they also recorded the date and occasionally various major events. We can "run the sky backwards" and compare with their records to get a perfect correspondence between their calendar and ours. This is why we know the exact date of the death of Alexander the Great, among other things.
An old or middle kingdom observatory with dated slabs that describe enough events to get us a few unambiguously fixed dates is one of those finds that archeologists dream of.
