The dramatic events of the interwar period constituted a watershed, separating millennia of interconnectedness and interdependency in the Persian Gulf from an era of geopolitical rivalry and Arab-Iranian conflict. Indeed, these two decades heralded the dawn of economic and political modernity in the Persian Gulf subregion. This period witnessed the collapse of the Qajar dynasty, the coming to the fore of Reza Shah Pahlavi and his assumption of the nationalist mantle, the introduction of nationalist policies into the Persian Gulf, and the incorporation of the Gulf Arab shaykhdoms into the Arab nationalist awakening. Reza Shah’s Iran took issue with Britain’s dominant position in the Gulf and rejected its claim to protect the Arab shaykhs of the southern littoral and strove to make Iran the main security provider in the Persian Gulf waterway. Iran’s ambition to gain sovereignty over the entire Persian Gulf region and regain territories of its former days was an ambition that resonated in the minds of many Iranian people. Iran’s bellicose policies also made a substantial and lasting impression on the rulers and inhabitants of the Gulf Arab shaykhdoms.

The geopolitical rivalry between the Gulf Arab states and Iran has its origins in the interwar period, the period between the Paris Peace Conference in 1919, which marked the end of the First World War, until 1941 when the Persian Gulf became a theater of the Second World War. The interwar period was a formative period because it marked a transition from a Gulf society characterized by symbiosis and interdependency to a subregion characterized by national divisions, sectarian suspicions, rivalries, and political tension. The introduction of Iranian nationalism to the Persian Gulf waterway, islands, and littoral and the unprecedented interventions of the British government in the Arab shaykhdoms including Kuwait, Qatar, Bahrain, Dubai, Abu Dhabi, Sharjah, and Ras al-Khaimah, constituted a watershed in the history of the Persian Gulf, disrupted centuries of unrestricted movement, refashioned frameworks of exchange between the two shores, and forged an acute Arab-Iranian dichotomy that would characterize the Persian Gulf into the twenty-first century.

This chapter discusses Iranian nationalism during the years of Reza Khan’s rise as a nationalism rooted in territorial concepts. It describes how the emerging military rule of Reza Khan coalesced with the foreign policy efforts of the Iranian statesmen until parliamentary politics were overshadowed by the military’s arbitrary rule. Against this backdrop, the greater part of the chapter is devoted to depicting Iran's policy toward the Persian Gulf and toward the Arab shaykhdoms in the Gulf during the period of Reza Khan's rise, and the rhetoric and conduct of Iranian officials in the port towns and islands where the paths of Arabs and Iranians from different walks of life intersected. The assertion of central authority over Arabistan (renamed Khuzestan) is viewed as a decisive step in Iran’s more ambitious goal of reducing British influence in the Persian Gulf waterway, islands, and littoral.

This chapter examines the intersection between Trucial States, Iran, and the British during the interwar years with a particular emphasis on the crises of 1926‒1929. The events surrounding Iran's reoccupation of Hengam in 1928 and capture of an Arab dhow off the coast of Greater Tunb Island can serve as an apt example of how the Arab rulers and merchants of the Gulf perceived Iran and the British during the interwar years. The chapter concludes with an examination of the shifting power distribution within the shaykhdoms in the 1930s, due to the collapse of the pearl industry and the rise of revenues from air and oil agreements, with particular attention to the position of the Iranian immigrant communities in the Trucial States

This chapter analyzes Iran’s policy toward the Persian Gulf during the reign of Reza Shah Pahlavi. The analysis is roughly divided into three periods: the years of 1925‒1932, during which time Reza Shah's court minister, Teymurtash, tried unsuccessfully to regularize the situation in the Persian Gulf through negotiations with the British government; the year of 1933 during which time various crises in the Persian Gulf arising from local challenges to British authority became part of the negotiation process; and the period of 1934‒1941 during which time Iran, encouraged by British withdrawal from Hengam and Basidu, strengthened its reliance on the tactics of deception, bluff, and intrigue in pursuit of its aspiration to obtain a paramount position in the Persian Gulf. This analysis is preceded by a brief discussion of the nature of the Pahlavi state because it provides the necessary context for Iran’s policy toward the Persian Gulf.

This chapter focuses on the intersection between Bahrain, Iran, and the British during the interwar years and the influence that contacts with Iran and Iranians had on the process of nation and state building in Bahrain. It analyzes the role of Iran and the role of the Iranian immigrant communities in the evolution of the Bahrain administration and the emergence of Arab nationalist sentiments in Bahrain. It depicts how different elements of the Iranian communities viewed Iran, the Al Khalifa ruling family, and the British. And it explores how the Al Khalifa and different segments of Bahraini society regarded Bahrain residents of Iranian origin and nationality. The analysis is preceded with a background on politics and society in Bahrain with special attention to the growth and characteristics of the Iranian immigrant communities.

This chapter highlights the primary features of politics and society in the Persian Gulf from the rise of civilization to World War I. It provides a survey of state-tribe relations in the Gulf from antiquity until the introduction of European powers. It will then turns to a consideration of the triangular relationship between states, tribes, and foreign powers in the Gulf, with an emphasis on the period of British supremacy. It identifies the appropriate theoretical tools pertaining to tribes and tribal politics in the Arabian Peninsula, which can be used to better understand how British intervention was viewed by the tribally organized societies situated around the Gulf's perimeter. The advent of nationalism in Iran and the consolidation of Iran's frontiers beginning in the late Qajar period are discussed as well as the waves of Iranian immigration that laid the foundations of politics and society in the Gulf Arab shaykhdoms. The chapter concludes with an analysis of the profound changes that were beginning to take shape in the regional system on the eve of World War I.