The Namori Cataclysm was a massive event that occurred approximately 3000 years ago, when the Kaa Taan became angry and destroyed all civilization, centered on the capitol, which was completely annihilated and is now known as No Man's Land. Very little architecture was left intact, aside from Kanestronia Cathedral in Ramsalon Dawnport Crystal, the Cemetary of the Abyss in Candenord, the Elven Portal Network, and a few other monuments. Very few artifacts were left, and even fewer have survived to the present day. All those that remain intact were very powerful, including the Elemental Scepters and tomes written by Averatos (and subsequently discovered by a teenage Necromos).
It's almost impossible to divinate past the Cataclysm. There is what feels like a wall of painful static and interference. Even if a diviner beats the difficulty to see that far in the past, they'll rebound against this wall and get a massive headache for their trouble.
In addition, any knowledge or item from before the Cataclysm requires explicit Setting approval.