When the Islamic State (formerly known as ISIS, or the Islamic State of Iraq and Syria) conquered the city of Sinjar on August 3, thousands of Yazidis fled to the mountains. Many of the men who stayed behind were executed—some apparently buried alive—and many women were taken as wives (or, rather, slaves) for Islamic State fighters. The Islamic State’s particularly brutal treatment of the Yazidis was based on their strict interpretation of Islamic law, according to which certain groups, including Christians, Jews, and “Sabians,” can be tolerated as “People of the Book,” but others such as the Yazidis have no choice but conversion to Islam or death. The actions of the Islamic State in Sinjar put the very future of the Yazidi community of Iraq in jeopardy. Today the Yazidis are one of a number of minority religious groups in the Middle East who are at risk of disappearing completely from their ancestral homelands.

In Heirs to Forgotten Kingdoms Gerard Russell, a former British diplomat, tells the story of these groups and his journeys among them, from Egypt to Pakistan. As the book’s title suggests, Russell is fascinated with these religious minorities because of the way many of them have preserved ancient cults whose roots are independent of Judaism, Christianity, or Islam. Russell opens the introduction provocatively: “Imagine that the worship of the goddess Aphrodite was still continuing on a remote Greek island…. In the Middle East, in contrast to Europe, equally ancient religions survived.” It is these religions whose survival interests Russell. In all he tells the story of seven communities: Mandaeans (often described as “Christians of St. John,” but in fact not Christians at all), Yazidis (or Ezidis), Zoroastrians, Druze, Samaritans, Copts (who are of course Christians, but whose social situation is similar to the other communities), and the Kalasha of northern Pakistan.

What these groups have in common is that they have managed to survive in what have become mostly Islamic societies. Russell explains how the Mandaeans were able to survive partly because of their remote location in the marshes in southern Iraq where the Tigris and Euphrates rivers meet. There they practiced a religion marked by repeated baptism ceremonies, astrology, and spells. In order to avoid persecution by Muslim Iraqis the Mandaeans came to identify themselves as “Sabians,” as the Qur’an (2:62; 5:69) names “Sabians” (along with Jews and Christians) as a group “upon which is no fear.” Early Muslims were not certain who these Qur’anic Sabians were, and the Mandaeans took advantage of their uncertainty to claim this title, and thereby to win a tolerated status in Islamic society along with Jews and Christians. In recent years, however, the condition of the Mandaeans has changed dramatically for the worse. In the 1990s Saddam Hussein drained most of the marshes of southern Iraq in an effort to deprive the Shiite rebels of a refuge. This, together with the pressures of modernity, has led most Mandaeans to leave their ancestral home for other cities in Iraq or for the West. In fact today more Mandaeans live outside Iraq than inside. Those Mandaeans who remain in Iraq have been exposed to kidnappings and forced conversions at the hands of Sunni Islamists.

The experience of the Yazidis (who number about seven hundred thousand worldwide, about ten times larger than the Mandaean population) has been no less traumatic. Yazidism, which may have roots in pre-Islamic Mithraism, has been heavily influenced by Islam and in particular by Sufism. (One of the founders of Yazidism as we know it was a Muslim Sufi named Adi ibn Musafir.) The central figure among seven holy beings in Yazidism is the “peacock angel,” Malak Tawus, a manifestation of the unknowable God. Yazidis recount a story about Malak Tawus that is similar to one the Qur’an tells about the devil—namely, that he refused God’s command to bow down to Adam (Yazidis, unlike Muslims, hold that God forgave him). For this reason, Muslims (and others) have often accused Yazidis of devil worship, even though Yazidis do not think of Malak Tawus as the devil or Satan. When the fighters of the Islamic State took over Sinjar, they announced on social media their victory over the “devil worshippers.” With the decline of the secular state in Iraq and the rise of Islamists, the Yazidis of Iraq—unlike Yazidis in non-Islamic countries such as Armenia and Georgia—find themselves in extreme peril.

The Zoroastrian community of Iran is also in peril, although not because of jihadis. Today this community, centered in the ancient desert city of Yazd, numbers only around ten thousand, though there are about a hundred fifty thousand Zoroastrians worldwide. In Heirs to Forgotten Kingdoms Russell describes how difficult it was to find any Zoroastrians when he travelled to Yazd, and how the hills (or dakhmas) where the bodies of the Zoroastrian dead were once exposed have fallen out of use. But Russell also notes the widespread appreciation in Iran for the country’s Zoroastrian heritage—in contrast with Iraq, for example, where there is little interest in the country’s pre-Islamic traditions. Indeed the most important holiday in Iran is still Nawruz, a New Year’s festival rooted in Zoroastrian tradition.

***

Unlike Mandeanism and Zoroastrianism, the Druze faith is not pre-Islamic. It emerged during the period of the medieval Shiite Fatimid empire and was influenced by Pythagorean and neo-Platonic ideas. Whereas the Mandaeans seek legitimacy in an Islamic state by identifying themselves as Sabians, the Druze survive by keeping their religious doctrine secret. To outsiders the Druze present themselves simply as Muslims. In fact, the inner truths of the Druze faith—revealed only to certain members of the community who have gone through initiation rites—are dramatically different from Islamic teaching. The Druze faith teaches that God manifested himself on earth in the form of the Fatimid caliph al-Hakim, and that Islamic law has been abrogated. The Druze are a large community in Syria, Lebanon, and Israel (numbering almost 1.5 million) and they have largely avoided persecution. In the West, however, the Druze have struggled to maintain their identity.

One of the most surprising chapters in Heirs to Forgotten Kingdoms is about the smallest of all the groups Russell met in his travels: the Samaritans. The remaining eight hundred Samaritans live in two places: a single neighborhood in Tel Aviv or a small village near the West Bank city of Nablus on top of Mount Gerizim, where, according to Samaritan belief, Adam was created, Abraham made his sacrifice, and the true temple of God was built. A century ago there were only about a hundred twenty-five Samaritans left. Faced with extinction, the community was able to grow again because of strict rules against marriage outside the community (with an exception for women marrying into the community), positive relationships with both Jews and Palestinians, and the virtual end of conversions to Islam since the establishment of the State of Israel. Of all the religious communities Russell writes about, the Samaritans are the only ones who seem to have a bright future in their ancestral land.

By contrast, the Copts—or Egyptian Christians—are by far the largest community covered in Heirs to Forgotten Kingdoms, numbering 5 to 10 million. Yet they have suffered both from systematic discrimination by the state and from regular acts of violence. Russell describes how various Egyptian leaders (notably Sadat) have sought to win the support of Islamists by having state schools glorify Islam and ignore Christianity and by enforcing traditional elements of Islamic law, such as the prohibition against the conversion of Muslims to Christianity or the marriage of Muslim women to Christian men. At the same time, attacks on churches or Christian homes—often prompted by rumors that a Christian man has slept with a Muslim girl or that a church is being built or repaired without a permit—have become alarmingly common. This is partly because the state has been notoriously weak in punishing acts of anti-Christian violence. For example, when sixteen Christians were killed in a single incident in 2000, none of the perpetrators received a prison sentence of more than two years. At the same time Russell describes the general rise in piety among Copts, and suggests that this is not a coincidence. He quotes one Egyptian Christian as stating, “As long as you feel threatened by the others, your identity will be strong.”

Finally Russell describes his 2012 visit to a remote corner of northern Pakistan where the Kalasha, a small community of about five thousand, have preserved their pre-Islamic polytheistic religion. As recently as a hundred fifty years ago, a large area of what is now northern Pakistan and eastern Afghanistan remained polytheistic. It was known to Muslims as Kafiristan, “the land of the infidels.” A campaign of forced conversion led almost all its residents to embrace Islam except for those in three Pakistani valleys. Since then, the Kalasha’s religious festivals have become popular tourist attractions, and some Greeks have invested in schools meant to preserve the religion, language, and culture of the Kalasha, who are believed to be descendents of Alexander the Great. Nevertheless, the Kalasha religion remains at risk of extinction. Conversions to Islam continue, and in Pakistan—as in so many other Islamic countries—once someone has converted to Islam, there is no going back.

***

In books about Islam or Muslim-Christian relations, it is often said that Islam has traditionally been comparatively tolerant of minorities. Heirs to Forgotten Kingdoms complicates that portrayal. It describes the “great harshness” with which the Zoroastrians have been treated in Iran (where, for example, they were not allowed to testify against a Muslim in court). Samaritans, we learn, were required to wear bells in public and were prohibited from riding horses until the eighteenth century. In the 1830s, twenty thousand Christians from the Church of the East died in a massacre organized by the Ottomans. Today, with the rise of the Islamic State in Iraq and Syria, the hardline Islamic regime in Iran, and the increasing radicalization of Pakistan and Egypt, the situation of religious minorities in the Middle East seems worse than ever.

Maybe this is why Russell includes an epilogue about the growth of Middle Eastern minority religions in the United States. Yazidis have settled in Buffalo and Lincoln, Nebraska, while the Church of the East is building churches in Detroit. Russell even describes a Mandaean baptism in the Charles River in Boston. Yet he also notes that the transplanting of Middle Eastern religious minorities to the West has been a double-edged sword. Members of these groups have found safety and sometimes success in their adoptive country, but they have also found it difficult to maintain their community’s identity and religious commitment in the face of pressures to assimilate. As Russell writes, “I wondered whether coming to America must always be a back-loaded contract for immigrant communities—get the benefit of prosperity now, pay the price of loss of identity later.” One Mandaean American puts this more dramatically, insisting that the U.S. policy of welcoming Mandaeans under asylum laws is “saving Mandaeans, and killing Mandaeanism.”

So what can be done to support religious minorities in their ancestral homeland? Russell argues convincingly that any programs meant to help Christians (or other minorities) in the Middle East must also help their Muslim neighbors. He also argues that “violence comes at the end of a long process of radicalization” and insists that the West must encourage countries in the Middle East to work against the incitement of religious hatred. The place to begin is the educational curriculum. In the end, Heirs to Forgotten Kingdoms is much more than a catalogue of obscure religions in the Middle East. It is as much about Islam as it is about minority religions, and it raises questions about religious freedom, interreligious relations, and tolerance that should concern believers in any religion, or none.