This was also the time of Alexander the Great... who was destined to be cut off by sickness in another part of the world. (VIII 3)
Livy puts this comment into the middle of Book 8 but says almost nothing else about Alexander the Great. Mentioning Alexander at this point exposes something about his thinking and that of his audience. The first is that it establishes his chronology- as though for example I were to describe the discovery of certain ideas of quantum mechanics as occuring just before or just after World War 2- it locates what he is describing. In that sense, what Livy's locator gives testimony too is the centrality of Greek history to a Roman understanding of the past. When we think about the way that Roman elites thought about politics, we should never think about Roman history alone but also the Greek comparison. Perhaps this is clearest in the work of Plutarch, a Greek, who wrote accompanying lives- one Roman, one Greek- but this reference exposes its relevance for Livy. Writing a history of Rome, Livy wants to fix it to some familiar dates in his readers' minds- one set of well established and familiar dates are the Greek dates and events- hence we see Alexander the Great arrive on the scene very briefly.