The Cumans were the main antagonist of the first game, and they first show up in Kingdom Come: Deliverance 2 in a side quest as well. Here’s how to find the Cumans’ Camp in the Invaders side quest in Kingdom Come: Deliverance 2.
The Invaders side quest can be accepted and started pretty early on in Kingdom Come: Deliverance 2. Once at least a couple of days have passed since you’ve parted ways with Hans Capon, go back to the inn in Troskowitz and speak with the innkeep. She’ll tell you that the Cumans are making the locals a little antsy, then ask you to serve them.
This will mark the start of the Invaders side quest, and you can speak with the Cumans to take their order, or refuse to serve them. Either way, a fight will eventually break out between the Cumans and the townspeople. Depending on your dialogue choices with the Cumans, you’ll need to side with one faction or the other.
Regardless of how this fight ends, the Cumans will leave, and Vuytek will ask you to make sure they never return to Troskowitz.
To find the Cumans’ Camp, you can do a bit of investigation first by speaking with the people in Semine. Head over to Semine, which is far southwest of Troskowitz, and speak with Lord Semine to learn more about the Cumans.
To cut straight to the chase, the Cumans’ Camp is located just southwest of the Nomads’ Camp, which is west of Zhelejov. I’ve included a screenshot of the map down below to indicate its location.