...sorry, my memory has grown dim on this issue. But as far as I remember, wall ownership and models used was
defined in one of these files, as noted above:

For campaign map models:
- data/descr_cultures.txt
- data/descr_sm_settlements.txt

and for the buildings and stats used in battle:
- data/descr_building_battle/dbb_walls_greek.txt (for example) for the stats. In this file, please ready my annotations. They are about 2 years old, but still describe what I originally did to the walls. Be very careful when you edit things here.
- these files (dbb_walls_greek.txt for example) are referenced to towards the end in data/descr_building_battle.txt, and (perhaps) data/descr_items.txt, btw.
- data/descr_walls.txt

And I also remember that some factions use other walls than you would expect them to in vanilla rome; foe example, the greek factions originally use the roman walls on city leven 4 and 5 (or so). Now the greek_huge_city_wall_gate.item file or something in fact does exist, but it is "broken" in a sense that it does not fully function. So what I did was to define new wall ownerships where appropriate. now the funny thing is, this was about the only step I didn't do and document in a way other people could easily understand afterwards. For example, I gave ownership of some of the greek walls to the egyptians and vice versa, to be able to come up with new textures for each faction... it is stupidly confusing now even for me, but I remember this was the most effective way of doing things back then. Forgive.

To give the Yomi their new walls I used... damn, what did I do... I think I used the chinese walls and gave them a new texture in both 3DS Max and... where was it... yes! In descr_building_battle.txt. Due to a bug with the export function for ITEM files in 3DS Max I actually had to give the egyptian (Yomi) faction the new texture several times with different names... take a look at my documentations in that .txt file and you should be able to guess what I did in this case.

I am sorry. You discovered my weak spot; wall stuff was the thing I did *not* take the time to do in an orderly fashion...