There are more and more new civs and city states out there, here's a small tutorial on how to edit an existing custom map to add them using the World Builder. Prerequisite: working mods in standard game ! I'll take Yet Another Giant Earth Map, Scotland civ and Not Another City States Mod as examples here. One of Yagem maps will be used as a base, we will replace Edinburgh by Scotland and add the Pygmy Nation city state. First thing to do when you load the World Builder is to check the mods the map will use : Spoiler : In fact, it may be a good idea to check ONLY the needed mods. Once done, the WB will take a few seconds to load the mods, and you can click on "load map". The defaut path is set to the map folder, the map we want to change is in a mod, so we must navigate to the mod folder: Spoiler : The map is now loaded, you can scroll using the keyboard arrows or the mouse (with right button pressed). Notice the grey circles, that's the start positions already set. Spoiler : Now open the scenario editor. While here, you can change the game options as it's not possible to use a scenario and the advanced setup at the same time... Back to the point, we want to replace Edinburgh with the Scotland civ, we'll begin by removing the Edinburgh CS. Click the City States tab, select Edinburgh, then click the minus button. Spoiler : Now that Edinburgh has been removed, you can notice if you go back on the map that the grey circle at the city starting position had also be removed. To add Scotland, click the Players tab, the add button and select the new civ then use the civilization menu to set it to Scotland Kingdom. Spoiler : Now, we'll add the Pygmy CS in the game the same way but in the City State tab Spoiler : Back to the map, let's set those starting location ! We must be in the edit plot tab of the map editor tools, select a plot by left clicking on it, then go to the start location menu and select the civilization to add (Scotland here) Spoiler : Please note that if we had just added Scotland and changed the start location of Edinburgh by Scotland, then Edinburgh will be spawn randomly on the map. All civs and CS set in the scenario editor are spawn on the map when you load a scenario, even if their starting location is not set ! that's why we've removed it first Now, let's find a good starting location for our Pygmy Nation Spoiler : We're almost done. At this point, you can save, quit and load you map and enjoy the changes. But to prevent strange bugs, I now use another step... Here's an example from one of Yahem map, where some case of sharing vision happened at start, even if each civs / CS was set as a separate team. In the scenario editor, be sure to set team in order, for example : Spoiler : Here we have US set as team 39, that should not be a problem, no other civs / CS use this team number, but still US shared vision with a City state from across the map.. So after removing/added a few civs and city states, I renum all team from 1 to last civ, then I renum CS from last civ +1 to last cs Spoiler : Now you can save and have a good game !