While I can't offer much more, your best bet is to read the Pocket Guide to the Empire, both volumes 1 and 3, which is the foundation on which most of the lore of the series has been built. There are probably other texts that also help, but others know that area of the lore much better than me and would be better able to point you to which texts are ideal.
Also, careful about those wikis. The wikia is the worst of the lot, and even UESP has a lot of unsourced and incorrect speculation on it. UESP is good for actual, in-game information, but take the whole thing with a grain of salt. Your best bet is The Imperial Library, imperial-library.info, which contains every in-game text.