Wait, are you saying that you don't see how rea;-world colonialism can apply to Septim colonialism? In this one alone, we have them imposing western idea(l)s on a decidedly nonwestern civilization in an attempt to rewrite their culture and thereby control them. We have what is by all accounts an idylic society being dismantled and remade under the 'progressive' norms of Empire. This culture is viewed as at once naive/innocent and conniving/duplicitous. They slaughter the native populations, and then only stick around for the considerable economic benefits.
I understand how the Cyrodiilic colonialism is
reminiscent of British style colonialism, but the Cyrodiil Empire wouldn't be all that interesting if it was just the British Empire with a different name. There's a lot more that goes into it, drawn from many civilizations, and if the devs did their job right, we aren't left with a clearly defined facsimile or collage of easily identifiable real world references.
And maybe I just read the story wrong, but at what point does Uriel slaughter everyone in Cathnoquey?
But to answer your question, I do see what parts of Cyrodiil are drawn from history. You have the Imperial Legion that represents the Roman Legion, in look, name, and partially in structure and actions. There's the idea of holding provinces, which is also notably Roman, yet the idea stretches back farther to the Persians, and even farther to the Egyptians, and the hosts of Hellenes, not to mention the Assyrians and an actual ancient Iranian people called the Medes (defeated by Cyrus [go figure] the Great) and the Mauryan Empire in ancient India. There are empires throughout history that have done a lot of the same practices, so it doesn't make complete sense to say that the Cyrodiils are completely based on one in particular. Rather to say they are based upon they
idea of Imperialism with the skin of real life cultures grafted, hopefully skillful enough to where we as the audience can't see where one real life culture begins and another ends, thus they become the Cyrodiils and Septims rather than just Romans and British.