I'm afraid a lot of the material I worked with was not specifically leftist, and the fact of the matter is that that sort of thing is outside of my field of expertise. With that big BUT out of the way, Kennedy's The Rise and Fall of the Great Powers is the closest I've read to a materialist take on the subject - the book places great emphasis on productive capacity, or the means of production, as the true core of a state's power. The predictions, such as a declining US due to imperial overstretch and excessive military spending and China's rise (this was written during the Deng era) turned out to generally be correct I would say. One minor nitpick I found was that the section on the Second World War indulged a bit on Wehraboo stuff, (something about the Nazi army being higher quality) but this was also the time that Guderian and Halder's bullshit was still prominent in military historiography so :shrug-outta-hecks:. In terms of time frame, the book basically covers from about when the Habsburgs were the hegemonic power of Europe to around the accession of Deng.