Mass Grave from the Second Battle of Himera, Sicily, 409 BC
DNA analysis of the remains from this burial pit shows that about a quarter of the "Greeks" who fought in this famous battle against Carthage were non-Greeks, most likely mercenaries. Graves said to be associated with the First Battle of Himera in 480 BC were more than half non-Greek.
That's a big image worth clicking on if you like this sort of thing. (NY Times)