I've been stumped on my fanfic for far too long. Every time I thought I'd managed to clarify just what had happened in the past, it made it even more plain it didn't happen in New Mexico. Where I'd put my characters as of the previous chapter.
So back to primary sources. I watched all the Tomb Raider: Anniversary cutscenes. And oh my. Apparently the White Sands area was a seat of power for Qualopec. Complete with Mesoamerican-style pyramid, surrounded by (!!) what look like Olmec heads. Cripes.
So I'm going out on a Doylist limb here. These aren't flashbacks, after all; they are visions Lara is granted when she assembles the Atlantean Scion. So call them a little confused, the way visions are. Oh, and the opening scene? It's obviously wrong already -- there was only one atomic test in 1945, it wasn't at Los Alamos itself, and it most certainly did not include the buildings of a mock-up town getting blown down. But, hey, the cutscene starts in black and white anyhow. So call it a documentary, with some fudging of the facts for better dramatic impact. And Natla did not fly, burning, out of the crater whilst the mushroom cloud was still growing.
This is far too tempting a road to travel further and further, of course. I'm strongly leaning towards deciding that re the Stargate universe, nothing is canonical that hadn't been shown by the end of Season 4. So I don't have to stick with some of the really absurd stuff about Merlin, for instance.
One is further tempted to assume that everything you've seen about Lara's adventures actually comes out of one of the highly dramatized fan magazines (or ghost-written accounts, before she decided the publicity wasn't actually helping). So Atlantean script looks half-way like a reasonable language, and not like the crazy hodgepodge of cabalistic signs and ersatz hieroglyphics shown on screen during the game. And maybe it wasn't really a t. rex. Ah, but that way lies madness.
Part of the fun of the fanfic game is sticking with what was actually in the original, and making an effort to explain it (or at least make it seem to make sense).
But when you get down to it, as fascinating as the question is of what the Ancients were up to prior to 2 MYA and after 10 KYA (the dates the show gives for their two sojourns on Earth), particularly their interaction with human (and homo neandertalis) migration, the neolithic revolution, etc., the schema I have for my story isn't going to allow any of the characters to actually figure it all out. It's going to be a mystery to them. It might as well be a mystery to the reader as well.
Trouble is, I do sort of have to know myself. Because I'm still trying to figure out what the hell Natla was trying to dig up in New Mexico (it can't have been the infamous UFO, despite this taking place not far from Roswell). Or why there's a History Channel group of pseudo-archaeologists there now with their video cameras. Or why Amanda was there, and why the heck she thinks Lara Croft would soon follow!