The Markings on the cave walls, Copied down by Kleden, appear to be a series of pictorial glyphs.
When translated they read:

Those beyond time I tell,
The shame of my people.
Our cities golden and green,
magnificent to behold.
Our souls ours to bend,
With power no end.

When our anima began to wane,
We drew our strength from blood and pain.
Our ignorance, Arrogance, Greed,
did birth a god, mad and depraved.

O’ Ouroth, devourer of all.

Our spirits swelled,
Our hearts grew cold.
In conquest we went,
to slaughter the weak.
To our Allies of old,
arms of leather and stone.
Bloodshed and horror,
our fates we had sown.

O’ Ouroth, devourer of all.

In our hubris we did not see,
the power of our enemy.
Their minds linked as one,
A song rivalled by none.
O’ Ouroth, mighty serpent,
unmade by thought and fury.
Your poison unleashed,
our land now deceased.

Chaos blooms,
Kingdoms end.

Now we are but husks,
a race forgotten.

Other markings, near each cross on the map have also been translated