Hey, srpt, what you think in add barbarian civs in this mod? I have a few suggestions:
Scythians
Start in 300 BC(they are in this period a decadent civ, plagued by the attacks of the sarmatians and the celts - they can be represented in this moment like a barbarian waves)
UP: The power of the fertile steppe(the scythian -Ucranian- steppe are less harsh than others steppes like the mongolian): All steppes tiles in the scythian steppe have More 2 food plots.
UU: Virgin maiden, a horseman(horsewoman

) which start with 2 flanking.
UB: Kurgan, a monument ( I know, we have MANY monuments, however the kurgans are so unique and special for this tribes which is impossible discart it) which give a extra trade route.
UHV:
1° own by controlling resource or by trade 3 wine and wheat resource by the 100BC (The scythians have so many wheat which they export it to the Greeks, and of course the scythians really LOVE WINE!! Herodotus said it!)
2° Make the cities of Olbia, Tanais and Cheronessus the biggest commercial centre in the Europe and middle east in 75 BC.(This cities are important centre of trade in this period)
3° Control the Scythian Steppe, Sarmatian Steppe, Caucasus, Armenia, Pontos, trapezzus, Moesia(Mikra Skythia), Thracia and Macedonia in 50BC.
Sarmatians(representing many tribes of then like the roxalani, alanni, lazyges and etc.)
start in 200 BC in the Sarmatian Steppe(representing a sarmatian emigration)
UP: Power of the superb cavalry: all of your horses units have 2 drill promotions.
UU: Roxalanni lancer, a lancer with 50% vs horse archer and 50% vs melee.
UB: Animist studio,a forge with give +3 culture and more 2 xp for the mounted units.
UHV:
1° Eliminate or vassalize the Scythians and have at least 5 cities in the Sarmatian and Scythian steppes in 50BC (correct was the scythians are subjugated by the sarmatians in the 300 BC).
2°Control the provinces of the Moesia, Dacia, Thracia, Pannonia, Noricum and the Lusitania in 250 AD. (representing the raids of the lazyges and alans).
3° have a commercial relations with ate least 3 barbarian civs and the 2 civilized civs and dont lose any city by the goths and the Huns in 400 AD.(representing the powerfull commerce with this people have with the others tribes traded his animist art pieces).
Germanics
start in 300BC in Colonia agrippa and augusta Terevorum
UP: Power of the Black Forest: all units have 2 woodsman promotions.(representing the great ability of the germanics in ambush the romans in the Germania Magna)
UU: Suebi berserkers, a axeman which can give colateral damage, can be represented with a warrior dressed with bear skin and armed with a club or a axe.
UB:Comunal house, a courthouse, whioch can give +5 xp for foot units.
UHV:
1° Control all Germania, Belgica, Noricum, Pannonia and Mediolanum in 50 BC.(representing a unification of german tribes and te Cimbri invasion.
2°Secure which no have a romam cities in Germania, Pannonia, Noricum or Belgica in 30 AD.
3°Secure which all of your cities are conected by roads and have a market and a barracks in 50 AD, representing the amber route.
And you can change the name of terevorum to Augusta Terevorum, and add the city name of augusta vindelicorum?