Save Empire Earth

I thought there was a way to take away the ability to upgrade epochs through the tech tree. Perhaps I was wrong, does anyone know how to do this?

Edit: The purpose is to take away the ability of going from bronze to dark at the beginning of the game but eventually I want to return that ability so the game is supposed to be bronze-dark.

It is possible with tech-tree triggers I think, I'm at work right now so I can't check it at the moment. But I'm sure there is.

Ahh yes you're right, I knew I've seen it somewhere before. Thanks man.

Yep graveblood had it.
There should be a tech tree effect for it.