Cumans "Are OP" They aren't.

I don't believe they are, Their town center is appreciated but it will delay you unless your heavily investing in wood preventing you from going onto farms earlier, later a market and black smith.

Their siege access from an earlier age is appreciated but could use a new line of units for federal age siege. "two villagers and a log for a ram" you don't really have the gold or wood to invest too heavily without putting yourself at a major disadvantage.

walls. wooden walls are such a simple thing for any other civ to break in and kill a cuman player in federal age. So that's a major problem for any cuman player knights can easily kill a cuman.

Steppe lancers. They can be countered by walling with stone walls or by avoiding your enemies steppe lancers and raiding their base instead. Most people don't use stone walls.

Steppe Lancers will kill pikes but if you've got archers behind then you'll counter them. Gunpowder will kill steppe lancer in droves.

Elite version is slightly stronger but civs like the slaves have a total counter even with upgrades.

Their archer unit is nothing special, you can give your allys free units for a limited time by the 10 free mercs.

But it really only needs to be massed like cav archers to be effective.

Overall, They have a bonus for eco but they can be countered if you don't charge in blindly and have a plan to attack them.