his desire to annex those territories into his own Saudi domain. Imam Yahya demanded the return of all Idrisi dominion. That same year, a group of Hejazi liberals fled to Yemen and plotted to expel Ibn Saud from the former Hashemite Kingdom of Hejaz which was conquered by the Saudis seven years earlier. Ibn Saud appealed to Britain for aid. The British government sent arms and airplanes. The British were anxious that Ibn Saud's financial difficulties may encourage the Italian Empire to bail him out. Ibn Saud suppressed the Asiri rebellion in 1933, after which the Idrisids fled to Sana'a. Negotiations between the Imam Yahya and Ibn Saud proved fruitless. After a military confrontation, Ibn Saud announced a ceasefire in May 1934. Imam Yahya agreed to release Saudi hostages and the surrender of the Idrisis to Saudi custody. Imam Yahya ceded the three provinces of Najran, Asir and Jazan for 20 years and signed another treaty with the British government in 1934. The Imam recognized the British sovereignty over Aden protectorate for 40 years. Yahya submitted to the Saudi and British demands out of fear for Al Hudaydah. According to Bernard Reich, Professor of Political Science and International Affairs at George Washington University, Yahya could have done better by reorganizing the Zaidi tribes of the northern highlands as his ancestors did against the Turks and British intruders and turn the lands they captured into another graveyard. Although the imamate lost Asir, it was able to put down rebel tribes in the north using Iraq-trained Yemeni troops. With the country, now established within clearly defined territory, finally pacified, the urban nationalists began to assert themselves. These nationalists had long practiced non-Zaidi traditions (especially Shafi'i), and were centered in the coastal province of Tahama, the city of Ta'izz and the British-occupied Aden. Many had been students in Cairo and had acquired connections with the Muslim Brotherhood and Algerian nationalists. Muslim Brotherhood operatives in Yemen aligned themselves with the urban opposition and supported Zaidi prince Abdullah bin Ahmad al-Wazir, who joined those actively seeking to overthrow Imam Yahya. On February 17, 1948 the opposition revolted in Sana'a and killed Imam Yahya. Crown prince Ahmad was able to rally northern tribes and retake the capital, quelling the revolt after a brief siege on March 12, 1948. Imam Ahmad reversed the isolationist policies of his father and opened Yemen's economy and society to the outside