Both the Legend of Korra and the predecessor series The Last Airbender both are very much based in a fantastical world but take inspiration from a variety of actual Asian cultures and history, among others (e.g the Water Tribe draws elements from Inuit culture). One of the big strengths of the show is that it doesn't combine all of these borrowings from the real world into a single melting pot but instead has a diverse mix of cultures. To draw exact country-to-country analogies is not entirely accurate, as the links are more thematic than factual. The Fire Kingdom's imperial wars no doubt drew on the Japanese actions during and before WWII and a recent plotline regarding the Earth Queen had obvious echoes of the end of the Qing Dynasty in China.
This present season is all the more interesting as the tale has both historical and contemporary references. The Earth Kingdom is in shambles, and their are two simultaneous and at times contradictory efforts to restore order. The heir to the throne is a expat living in a rich neighboring city state who seeks to be coroneted and restored with the help of international forces. Meanwhile, a military leader from a powerful faction within the Earth Kingdom is gathering allies, offering security in exchange for pledges of loyalty. Here I do think they take inspiration from Chiang Kai-shek's work to reunify China and both the strengths and weaknesses of such a military-based approach.
I'm rather hopeful that this season will wrestle with the challenges our heroes will face trying to figure out how to deal with instability while facing the very real limitations and value conflicts with their allies in that goal. If this is done well, I hope it will inspire people to read more of the actual history as well as considering what to do in contemporary situations where the choices might be a good bit worse.