alt Hacker NewsI specifically meant live trees, didn't really occur to me that dead trees could be relevant. Not sure how common it is to find 12000 year old dead trees either but I guess it's more common than live ones.
And of course geological surveys would definitely tell you something about the past
Oak and other trees, felled several thousand years ago and used as trackway posts, in buildings, etc are the bread and butter of
* https://en.wikipedia.org/wiki/Dendroarchaeology
Art historians often look at the wood panels of paintings that are 400 years or more old.
You might enjoy reading the general overview: https://en.wikipedia.org/wiki/Dendrochronology
and, ahh, drilling deeper into the onion rings.
The real problem with tree rings here in this specific case is ... Ethiopia .. not a lot of big trees now, nor in the recent past when it was grasslands - but not really my field - there's likely to be very slow growing unassuming trees that are surprisingly old there .. and remains of older trees that have overlapping ring sequences.
But yes - geological / geophysical clues are likely more relevant here.