Murray answers four questions in just one episode sent in by David: 1. Were the legions largely (or even completely) replaced by the foederati by the seventh century CE? 2. What do we know about the ethnic makeup of the armies that fought for pagan Rome in the wars of the first centuries BCE and CE (largely legionaries from southern Europe?) compared to the armies that fought for Byzantine Rome in the seventh-century wars (largely "barbarians"?), including Heraclius's reconquest of Jerusalem in 628 CE from the Persian Sassanid empire? 3. Do you have a view (either way) on the argument—made most compellingly by Tom Holland in his 2014 book, In the Shadow of the Sword—that the Byzantine Roman army of the early seventh century was made up largely of fighters from the southern Levant and northern Arabia (where the Ghassanids came from)? 4. Could Arab forces that formerly made up the Foederati have "declared independence" from Rome in the third decade of the seventh century and ultimately have conquered the Levant from the Romans in the 630s (before engaging in civil war among themselves and the descendants of the Lakhmids, who had fought on behalf of the Sassanid empire three decades later)? In other words, might Muhammad and his original followers all have been former Foederati, who turned against their former Eastern Roman clients, much like the Gothic barbarians did against their former Western Roman clients a couple centuries earlier?