Although I know how to do that.....tech trees are very time consuming to create...
I just finished the new Ancient Age...and I think your going to like it. It combined elements of the old Far Horizon's Ancient age with elements of the Mesopatamia Conquest's tech tree.
Basically, I pushed the starting period back to pre-Sumeria. Stone Working, Pottery, Wood Working, Cuneiform, Cermonial Burial, and Warrior Code are now the first techs you can research. Settlers now become availible with Irrigation, thus slowing civ expansion. Also, this spreads out the life of several units that upgraded pretty quickly before.
BTW...heres the future age: