Across eight chapters, Chelsi Mueller narrates a detailed diplomatic history of the Persian Gulf between the two World Wars. By sifting through an array of sources, including British colonial records, published Iranian foreign ministry documents, and Arabic sources, she identifies this quarter century as pivotal, casting a shadow over relations between Iranians and Arabs to the present day. Reading these materials more with than against the grain, she concludes that the interwar era was “a watershed separating millennia of interconnectedness and interdependence in the Persian Gulf from an era of geopolitical rivalry and Arab-Iranian conflict” (p. 229). The reason for this was the Iranian state's “introduction of nationalist policies,” which both fueled the development of Arab nationalism in the Gulf Arab shaykhdoms and “invited” (p. 191) British “imperial intervention” into the affairs of what were then protected colonial formations.

After a concise introduction, The Origins of the Arab-Iranian Conflict begins with four lengthy chapters. The first is a synthetic and sweeping history of the Persian Gulf across many centuries. The Persian Gulf is described as an “integrated societal unit” and the focus of the chapter is on tribalism, “the absolute powerlessness of the Qajar government” (p. 37), and “the rise of the British” (p. 9). This background history does not depart from standard accounts, but its discussion is light on the forces that many historians evoke when representing the waters of the Gulf and Indian Ocean as a bridge instead of a boundary: the socioeconomics of pearling, trade, and seafaring; the circulation of religion, law, kin, and credit; and environmental and ecological patterns, including the climatic metronome of the monsoon winds. Later chapters gesture to the centrality of these matters, as well as the founding of industries for oil extraction, which sits squarely in the time period covered by the book.

Chapters 2 through 4 detail Iranian-British relations in the context of Iranian state-building and British imperial strategies to argue that “the Persian Gulf comprised a central theme in anti-colonial nationalist discourse in Iran” (p. 78). We learn a lot about the “zeal of local officials” (p. 47), the “shrill pitch” (p. 80) of Iranian nationalism, and “anti-British feeling in Iran” (p. 49). Mueller is interested in outlining how nationalism infused Tehran's policies and informed actions of local agents of the foreign ministry (kargozar), moving the discussion of nationalism from intellectual history to the machinery of the emerging central state through a close reading of the diplomatic record both before and after the coronation of Reza Shah. However, she does more than this. Iranian nationalism, the prime mover of this story, does not stop at Iran's borders. Some of the most engaging moments in these chapters are observations that Persian-speaking communities (both Sunni and Shiʿa) in the port cities of Eastern Arabia held ideas about Iranian sovereign territoriality and national belonging, and at various moments sought protection from Tehran. By the 1920s, some members of this highly differentiated population had organized and coalesced around newspapers, schools, and political parties, anchoring a sense of national identity at a moment of economic instability (i.e., the global depression, collapse of the pearling industry) and political and legal restructuring (i.e., decolonization, creeping bureaucratization of governance in these protected states). Armed with the vocabulary of nationalism, these “Iranian immigrants” (p. 181) or this “diaspora” (p. 159) made claims on officials in Tehran, Shiraz, and Bushehr for protection against both British regulations and the rulers of these protected Gulf Arab states. Meanwhile, journalists “churned out” articles for Tehran's and Shiraz's newspapers calling on the shah to defend Iran's claims on islands, ports, and shipping channels (pp. 80, 84). These bottom-up pressures may not have ensured Iranian rule over Bahrain or protected the rights and economic well-being of laborers, seafarers, shopkeepers, and merchants, but they did shape what Reza Shah and his court could accept after the infamous 1919 Anglo-Iranian Treaty collapsed and Iran engaged in negotiations with Britain about the oil industry, naval bases, customs regimes, quarantine procedures, and buoys and lights on the waterway. “The introduction of Iranian nationalism into the Persian Gulf waterway” resulted in Britain agreeing to some of Iran's demands (p. 157). Conversely, Britain responded to this nationalist posture by adopting more interventionist policies in the Eastern Arabian shaykhdoms, which gradually had been turned into protected states through a series of treaties and compacts during the nineteenth century.

Chapters 5 and 6 forgo the largely chronological arc of the previous chapters to move the narrative across the Persian Gulf and examine two distinct places. The first of these chapters examines the Trucial States (the United Arab Emirates after independence in 1971), and the subsequent chapter considers the archipelago of Bahrain, which was claimed by Tehran until Mohammad Reza Shah's 1971 about-face. Mueller contends that the reactions to Iranian nationalism gave birth to conflicts between the Iranian state and Arab shaykhdoms and “forged an acute dichotomy between Persian and Arabs” (p. 157). This hardening of ethnic boundaries and the coupling of Iranian and Arab nationalism is an important observation, and I would have liked greater elaboration of the adoption of Arabism across Eastern Arabia and its dialogue with Iranianism.

Some of the most compelling moments in Mueller's book occur when she sheds light on the Iranian immigrant communities in Bahrain, Dubai, and elsewhere, and in particular how they expressed Iranian patriotism, solicited the support of Tehran, and occupied positions of economic power and political vulnerability in these British-protected shaykhdoms. Mueller's careful tracking of the delicate diplomatic maneuvers and occasional moments of spectacular violence around symbols of authority are detailed and original. Passports and the location of anchored warships generate anxieties, but so do the hauling down and flying of one flag or another (e.g., pp. 72–75). These cases, as well as overlapping customs procedures and battles over the recognition of travel documents issued by various authorities, gesture to the incomplete and relational nature of sovereign territoriality and the carving up by Britain of sovereignty between itself and a series of recognized shaykhs. Nationalisms, Iranian and Arab, and British imperialism, capitalist and racialized, aspired to more abstract and fractured conceptions of sovereignty, but they were forced to confront complexities of textured social life as much as geopolitical rivalries. Mueller nicely illustrates this in her description of the less-discussed conflicts over the island of Hengam, the port of Basidu on Qeshm, and Bahrain, but also the more well-known and ongoing disputes over the islands of Abu Musa, Greater Tunb, and Lesser Tunb. As I finished the book, I was left with a sense that British policy in the 1920s and 1930s was one of partition, in which Arabs were protected and Iranians were rendered independent, yet foreign. Considering how Britain navigated its imperial exit in South Asia and Palestine, the partitioning of the Gulf into two distinct shores chimes with the broader constellation of sovereignty, territoriality, nationalism, and the late British Empire.

It was not always clear if Iran's actions and the mobility of the array of “Persians” were viewed as a threat by rulers, peoples of Eastern Arabia, or British colonial officers. Mueller points to moments of “reconciliation” between ruling shaykhs and Tehran (p. 200), shifting sectarian and class alignments, and many moments when British officials and rulers adopted distinct approaches on these matters (pp. 184–85). Further elaboration is left to other researchers, as is the question of what this era tells us about sovereignty, territoriality, nationalism, sectarianism, and decolonialism as the world shifted from imperialism to internationalism. Some of this analysis exists in secondary literature on the Gulf, including works by Omar AlShehabi, Nelida Fuccaro, Laurence Louër, and Kaveh Ehsani, among others. Mueller does not grapple with this. Similarly, it is not clear if the interwar period is a useful framing for what Mueller identifies as an epochal reconfiguration. The quarter century was not only an interregnum between great wars, but also entailed the collapse of the pearling sector, the formation of oil industries, the founding of modern absolutism on both shores, the era of anti-colonialism and global decline of the British empire, and the rise of international law and international organizations. To be sure, world wars mattered for the people and societies of the Gulf because the littoral was a battlefront and logistics hub (something surprisingly omitted from the book), but further reflection is called for in defining this period and refining Mueller's causal claims centered on an Iranian nationalism that shaped the actions of the British Empire, the ruling shaykhs, and the peoples living and working on the Gulf littoral.

The conclusion summarizes the book's arguments by exploring how they constitute the origins of the current moment of rivalries and military posturing between Iran, Saudi Arabia, the UAE, and the US. The reader is encouraged to see the events of eighty to one hundred years ago as the source of what is unfolding today and to draw analogies between Britain and the US as outside security guarantors. Yet, this is heavily teleological, and the book leaves little room left to ponder alternative possibilities and hidden trajectories. The Origins of the Arab-Iranian Conflict will be a key ingredient and conversation partner for those pondering these pathways and the legacies that make the Persian Gulf so fraught for so many.