From creator Saint_Michaels_ -- this mod is an extremely useful mod that you'll need for other mods you may want to download for specific architecture in different civilizations. Essentially its designed to separate civilizations from their architecture sets and create a duplicate all while keeping unique SLP files.
This way they can be individually placed and modded without effect other civilizations, to quote the creator:
“The unique SLP files are also exactly the same as the originals that the civilization uses, so one person can, for example, play only modifying the Vietnamese with someone who has the Vietnamese untouched but modded the Spanish & the Huns.”
Thus as mentioned by the creator allowing you to fully customise and mod the buildings and architecture of different civilizations to your liking.