I've also been trying to nail down specific dates for the backstory, and in my latest pass over all the books, I've run into an apparent contradiction in Pyramid of the Sky Pharaoh.
Page 57 states that Hakotep took the throne in –1653 AR after his father was killed; however, on page 7 of the Slave Trenches of Hakotep, it was already established that Hakotep was pharaoh in both -1660 AR and in -1655 AR. My guess is that the -1653 AR date was a typo, and that it was supposed to be -1663 AR. The other dates could have been the wrong ones, but if you move that five year segment to be after -1653 AR, it conflicts with the date of -1649 AR that is given on page 6 of Osirion, Legacy of Pharaohs as the date that construction on the Slave Trenches began.
I've looked for any posts that already address this, but with no luck. Has anyone gotten an official confirmation/clarification/correction for the conflict yet?
The two dates "set in stone" are Hakotep's reign beginning in -1653 AR, and the beginning of the construction of the Slave Trenches in -1649 AR.
Unfortunately, that means that the dates in the Adventure Background of "The Slave Trenches of Hakotep." That's totally my fault - I must have temporarily forgotten that negative years decrease as they go forward and increased them instead.
So here's the official clarification:
-1653 AR: Hakotep I takes the throne.
Change -1660 to -1653: Osirion was on the brink of war when Hakotep took the throne.
Change -1655 to -1650: Two Shory cities fly to Osirion's border in a show of dominance.
-1649 AR: Construction begins on the Slave Trenches.
Ah, everything will work out just fine, then. Thanks for clearing it up!