For how many years has there been intelligent life on Altera? Would it for an example make sense to find an ancient temple while IC?
I know that ptiber's character, Galim Aeltus, was an explorer. He made a shop, then converted to a museum, with ancient relics. He described some ancient temples and cultures in some texts to accompany the historical items.
By the old lore mandate you'd need permission to write about stuff that happened a long time ago but has otherwise been around up to the present day. However, there are a few "ancient" ruins scattered around the map for those who can find them. Ruined towns come to mind. If you want something specific you should contact Faelin and Somnastra.
From what I had gathered from the lore team when I was making my stories and creating historical relics and history, you have every right to create the past as long as you don't overstep the few things that are known about human/elves/etc history on this Altera, which obviously begins with the last Exodus for everything that is buildable (towns, temples, etc...). But the humans/elves/dwarves/etc were all the same present somewhere before the last Exodus, so you can probably still find a way to do what you are trying to achieve.
Altera's time is now 2260 (what's the year 0, what's the reason for having started noting years at that time? nobody has been able to answer me when I asked
) and so you have two millenias of history you can tap on when it comes to people, events, all that stuff... What you create won't be canon, and shouldn't approach any sensitive matter (no fanciful race creation, maybe even nothing that approach the Immortal Kings, Grief, the Gods...) but you can create subraces, tribes, people, related events, towns, countries and nations if needed... It could still have taken place on the previous Altera world if it's too old for the current one
(or even on the previouses ones, you can use the Exoduses as you please ^^)
I sometimes have related stories of ancient peoples, temples and relics supposed to go back quite far in time, with some approximative datation (made references to fictional books relating things going back to 1200, for example). But I made sure it always only presumed things, not stating as the one and only truth. Hearsay, oral stories passed from grandpas to childrens around the fire, things gathered from asking questions to people then making that into a book... All that stuff that can create history: that's the beauty of the thing, you just have to say it has existed for it to have existed (at least for you! and if other people choose to believe it, then it will gain in probability of having really existed, if you see what I mean
History is made by those who write History
). Just make sure to use common sense, and talk to the lore team if something might be fishy.
As Baron said, you can find several ruins, that aren't have any dating, history, or even references anywhere but in what you can create for them
Sure, the last Exodus is supposed to only have took place a few years/dozens of years in the past, so maybe you won't find very old ruins or temples here... But history timeline on HW is pretty loose, as loose as passing time can be for our characters