I just posted in the remarks on the mod something similar. The barbarian hordes are so far out of balance with the rest of the game it just isn't workable. I have to stop them or stop using the mod which would be sad.

Go to My Documents\My Games\Sid Meier's Civilization 5\MODS\City-State Diplomacy Mod (CSD) for Brave New World (v24)\DLL and open the AddDefines.sql file with notepad.

Either searche for 'horde' once and change the 0 to a 1 where it says SELECT 'QUEST_DISABLED_HORDE', (0)

If you want you can look lower or click find next and get to the frequency of the horde and change that. I am guessing that the higher you make the value the less frequent the hordes would be in the game. I just have them disables since I can make them smaller.

I don't know where you keep your My Documents folder but a lot of people leave it in the default C:\Documents and Settings\User etc... but it should not be too hard to find. Hopefully a better solution will be presented that is more balanced for the game.

Hmm, well that kinda sucks. Hopefully will be fixed, thanks for all that, I'll probably keep it like this though since I farm barbs for XP lol

Edit: Ah I think I have found it, you need to kill all barbs in and within a few tiles of the city state under attack. So it is balanced towards needing multiple civs to gang up on the barbs. Maybe just need a touch of weight in the AI to help against these, but otherwise it seems to be working, just needed to kill the ones around the borders as well -.-

Just remember that the barbarians literally cannot take the city no matter how much damage they do. It only gets taken if there are barbarians left alive at the end of the countdown. Good luck.

In my current game, I've had a horde take out a city-state on the final turn of the horde quest even though there were no barbs left in the area. I can send you the save game if you like.

Does anyone know if the hordes have been rebalanced?

https://forums.civfanatics.com/forums/civ5-general-discussions.375/ I have no idea what set up you are running for the game but this is the place to get your answer. There is the Community Balance patch project for Civ 5 which massively changes and improves the game. Most of it is modular I think. https://forums.civfanatics.com/forums/community-patch-project.497/ Check this out.