With Armenians and Georgians added, all civilization IDs shifted.
Copied from ~Jp (World's Edge Server Engineer):
Hey @everyone,
Here are the new mappings that will be going live with The Mountain Royals DLC.
Here is a recap of what has changed and what hasn't since the release of the Return of Rome DLC:
* The Options string and Match Types have not changed.
* Mapping #3 is the mapping for the June CU up until now.
* It has the fixed map IDs in it (-2 → fixed map ID).
* Mapping #4 is the mapping for the current PUP and will be going live on the 31st with The Mountain Royals DLC.