The context of this part of text is Chaos
:
Prophets foretell if its coming... Historians record its passing.
And the only ones who can fully understand it are those who have survived its reign
...
Could you please explain the phrase who have survived its reign...
I understand it in this way: The chaos conquered on the planet, and somewhere ages hence after it has gone, people who survived are the only ones who can fully understand it.
past
and the only ones who understand it at this point in time are survivors... because they survived its reign. Don't they? – arava Feb 10 '20 at 8:51