Monsoon Revolution: Republicans, Sultans, and Empires in Oman, 1965–1976 by Abdel Razzaq Takriti Oxford University Press, 340 pp., $125.00 Oman: Politics and Society in the Qaboos State by Marc Valeri Oxford University Press, 256 pp,, $70.00; $27.50 (paper)

1.

The Pipeline

On March 12, Iranian President Hassan Rouhani, together with his foreign minister, his oil minister, the head of Iran’s central bank, and other senior Iranian officials, took a short flight across the Gulf of Oman to Muscat, the capital of Oman. Occupying the eastern tip of the Arabian Peninsula, where the Persian Gulf meets the Arabian Sea, Oman belongs to a part of the Arab world known for its hostility to Iran’s Islamic Republic. Several of Oman’s closest neighbors, including Qatar, Kuwait, and the Kingdom of Saudi Arabia, have been fighting an increasingly brutal proxy war with Iran in Syria; Iran has at various times threatened to block tankers carrying Arabian oil from passing through the narrow Strait of Hormuz, which separates it from Oman.

But the purpose of this extraordinary visit—the first by President Rouhani to Arabia—was to discuss economic ties with Sultan Qaboos bin Said al-Said, who has been ruling Oman for more than four decades. Within twenty-four hours, the two countries had concluded an agreement to build a $1 billion gas pipeline across the Gulf of Oman and provide Iranian gas to Oman for twenty-five years.

The deal showed just how quickly Iran’s position in the world has evolved. When Rouhani was elected, in June 2013, Iran was suffering from years of economic sanctions and isolation by the United States, which had deep alliances with Iran’s enemies—the mostly Sunni monarchies on the other side of the Persian Gulf. Since then, Iran has reached an interim agreement with the US to negotiate a new nuclear program, Saudi Arabia has lost considerable influence in Washington, and the Saudi-led alliance—the six-member Gulf Cooperation Council, of which Oman is a charter member—is increasingly divided. In June, when Sunni extremists swept across the northern half of Iraq, there was even talk of Washington’s and Tehran’s growing shared interests in saving the country. Though little noted in the press, the leader largely responsible for this dramatic shift was Sultan Qaboos, a staunch US ally and, measured by years in office, the most senior of the Arabian monarchs.

Unlike his flamboyant peers in Qatar and the Emirates, Sultan Qaboos has long had an aversion to publicity. But over the past year, the seventy-three-year-old sultan has asserted his country’s interests in regional affairs with unusual vigor. In August 2013, he was the first foreign head of state to visit Rouhani in Tehran, where he also met the Supreme Leader, Ayatollah Khamenei; this was followed by revelations that Oman had secretly been the host for bilateral talks between Iranian and US officials that produced the breakthrough interim agreement last fall.

Then, in December, Oman publicly denounced a plan by Saudi Arabia to turn the alliance of Gulf states into a political union—a plan that was widely viewed as an attempt by Sunni…