Jason Kottke recently shared a map from Wikipedia displaying the homelands of every character in the Iliad. In his commentary about it, he says "I wonder if that level of mobility was accurate for the time or if Homer simply populated his poem with folks from all over Greece as a way of making listeners from many areas feel connected to the story — sort of the “hello, Cleveland!” of its time."
It's a clever joke, and I wanted to see if AskHistorians could support or deflate the idea. While it doesn't seem improbable to me that such a widespread cast could be assembled (especially among seafaring people), is there any reason to suppose that the breadth of the characters was exaggerated to hook a wider audience?
Homer's intentions behind the Iliad were primarily focused on the chaos of war depicted through the main cast's perspectives; so it's quite plausible that he exaggerated on behalf of either a way to open his audience or to exemplify the disarray that is war. It is not, however, unlikely for major battles to be fore-planned with participation from the many areas making up Greece. These battles would be fought by various armies combined to show homage to their primary city-state. The idea of traveling long distances for a single battle wasn't foreign in these times - In the Iliad, a chapter or two is focused on each king/Leaders contribution to their side by providing ships to display their wealth and care for the cause. sort of flaunting if you want to look at it that way.