Babylon have a UB : walls of babylon, 7.5 def instead of 5. Bowmen instead of archers ( 8 attack instead of 6 ) and their unique trait is Ingenuity. They get great scientists at double the normal rate and get a free scientist when they research writing.
The archers are surprisingly good for an early unit, the 1st great scientist comes very fast and can either be used to have a very early academy (+5 science from the ancient era is quite nice) or to acquire civil sevice or education a lot of turns before the opponents.
In fact, building a couple of libraries and filling them with scientists often gives you 3 great scientists very early, so you can get to renaissance ( research theology, sac great scientists to bulb education and acoustics ) very early. Once there, you can use 1 more GS and the rationalism social policies to get to biology and the industrial era very fast, unlocking all social policies. You need a little more than that but either the capital can produce a second GS, or you can build the great library or Oxford university for a free tech.
Normand