The question the text itself attempts to answer was asked in the 680s by the monk John Bar Penkaye. How, he asked, "'could naked men, riding without armour or shield, have been able to win... and bring low the proud spirit of the Persians?' He was further struck that 'only a short period passed before the entire world was handed over to the Arabs.'" For Penkaye, the answer was clearly that it was God's will. Kennedy attempts to update the answer for a world, thirteen centuries later, "where divine intervention is, for many people, not an entirely satisfactory explanation of major historical changes."

The text is arranged in separate chapters on the foundations of conquest and the various places conquered, from Syria and Palestine to Iraq, Egypt, the Maghreb, Transoxania, and Samarqand. There are also chapters discussing the furthest reaches East and West, sea warfare, voices of the conquered, and conclusions.

Particularly interesting, because the voices of the conquerors are almost universally the clearest and loudest, is the chapter on the voices of the conquered - "works, histories, apocalypses and poems, which give some insight as to how the people in the aftermath of the conquests regarded their new masters and what they considered to be the losses, and sometimes the benefits, that the conquests had brought them." The responses range in geography from "Spain in the west to the account of a Chinese prisoner of war in Kufa." They range in tone from a "denunciation of the Muslims as complete barbarians" by Sophronius, the Greek-writing patriarch of Jerusalem, to "Mar Gabriel's conviction that they were much better masters than his co-religionists, the Byzantines." The voices include Christians, Jews, and Zoroastrians, and are drawn from Greek, Latin, Syriac, and Chinese.

Many of the early Christian responses come to us in the form of apocalypses in which the coming of the Arabs, in a time also of plague and famine, was seen as one sign of the end times. Interestingly, there is a modern revival of apocalypses in America and elsewhere as citizens observe and/or participate in the various conflicts in the Middle East - the Israel/Palestine conflict, and the "war against terror" in Iraq, Afghanistan, and perhaps soon Iran. To see how widespread this revisiting of apocalyptic visions is, one need only do an internet search with some combination of the keywords 'end times,' 'terrorism,' and 'Islam'. Although most results seem to come from conservative Christian sources, all three Abrahamic faiths are represented. Kennedy does not address this modern recurrence of apocalyptic thought, instead remaining focused on the time of the conquests, but states that the "apocalypse is both faintly absurd and curiously moving. In it we can hear the voice of the subject population."

Other Christians saw the Arab conquests not as a sign of the end times, but as divine punishment. For John bar Penkaye "the Arabs were the instruments of God, sent to punish the Christians for moral laxity and, above all, for heresy; but for him both the Chalcedonian Church supported by the Byzantine authorities and their Monophysites were the real enemy." We must remember that at this time there were a number of Christian Churches, each claiming to be Orthodox, and there was much mutual enmity and even persecution. For John, the rule of Muslims "might be either good or bad depending on the behaviour of the Christians."