Inaba said:
Hm, Lihua herself is in a weird position in canon and is pretty much inextricably tied up with how CG China came to be.
Females don't inherit the throne under Chinese imperial succession, the single exception to that rule is Wu Zetian who came to power through the traditional power to power for imperial women - by being Empress-Dowager and thus the go-to choice for regent. So I think it's reasonable to go with a scenario where Lihua is daughter to one of the more westernized warlords that popped up post-Qing (namely, Chiang Kai-Shek aka Jiang Jieshi).
I don't remember the exact nature of the conspirators against her in the show, but I got the impression that they were eunuchs. It's a pretty common scenario and not necessarily a bad one - but I think I'd go for a scenario where the eunuchs and their relations are propping up Lihua against her detractors because she's their main path to power. It's not exactly an unprecedented scenario - the last Han emperors favored the eunuchs so much because the eunuchs were their go-to men for resolving 'human resource problems' aka 'grabby in-laws'.
Instead of the eunuchs as the opposition to Lihua, I'd go for a combination of regional warlords that were never pacified so much as coopted into her father's empire and thus understandably resistant to any centralizing tendencies and perhaps certain factions amongst the literati that were both essential to Chinese imperial rule and so often detrimental.
I think that would make for a more interesting scenario than the 'eunuchs selling out their country' story in canon.
Given the timeframe that Code Geass takes place in, it would make more sense if Jiang Lihua was the daughter of Jiang Jieshi's son, Jiang Jingguo, who would be 53 at the beginning of R1. (Although Lihua should probably be older).
Also, given the fact that China, or, more specifically, the Chinese military, is in a significantly better position than it historically was in the time frame, it makes sense that there are some significant alterations to the timeline of world history.
First and most obvious, the capital is at Luoyang, not Nanjing, as was the case for the ROC, or Beijing, as is the case for the PRC. Furthermore, China has control over the historical Qing territories, in addition to much of Central and Southeast Asia, India, and much of Oceania.
This immediately suggests that the Ming Dynasty had never turned isolationist, thus giving it much more influence over all of Asia.
Now, the fact that the capital is at Luoyang implies that the Manchus were driven back after the fall of the Ming, that someone else succeeded at (re)unifying China. The most obvious candidate here is Li Zicheng, who presumably did not offend Wu Sangui as he did in OTL, meaning that the Shun Dynasty succeeds the Ming, not the Qing.
Although I don't know much about Li Zicheng's personality or his foreign policy, I don't think that it would be too much of a stretch to assume that he and his descendants would continue Ming foreign policy in establishing suzerainty over various other countries.
Then, assuming that the Xinhai Revolution occurs again, in 1911 (1966 by the Code Geass timeline), that gives the new government just under fifty years or so to consolidate power.