Today, Taiwan—formally known as the Republic of China (ROC)—has no diplomatic relations with Iran. This was not always the case. As far back as June 1920, Qajar Iran and the ROC under President Yuan Shikai (袁世凱) signed a treaty of friendship that meant to politically unite the two Asian countries.  Both governments had faced similar challenges, struggling to maintain their independence and territorial integrity from the onslaught of foreign powers since the 19th century. The ROC, led by the Kuomintang (KMT, 國民黨), and Iran then formally established diplomatic relations in 1944.  Yet, the rise of the PRC injected uncertainty and instability into Taiwan-Iran relations during the early Cold War period and Tehran ultimately broke off diplomatic relations with Taiwan and recognized the People’s Republic of China (PRC) in 1971. 
Iran and ROC Accusations against the Soviet Union
After the outbreak of the Second World War, Reza Pahlavi, the Shah of Iran, announced his country’s neutrality.  However, Britain and the Soviet Union preemptively occupied Iran in September 1941 to prevent Iran from becoming an ally of Germany, led by Adolf Hitler. After the occupation, Reza Pahlavi fled the country, and his son Mohammad Reza Pahlavi was later enthroned. In February 1942, the Anglo-Soviet-Iranian Treaty of Alliance was signed, which acknowledged Iran’s independence and integrity and pledged the withdrawal of all British and Soviet troops no more than six months after the defeat of Germany. 
Nevertheless, after the Second World War, the Soviets had no intention of withdrawing their troops from Iran, especially from the northwestern part. The Iranian government criticized the Soviet occupation in the newly formed United Nations (UN) at the end of January 1946.  James Byrnes, the US Secretary of State, argued that the Soviet action was nothing more than an attempt to secure Iranian oilfields in Baku, near northwestern Iran. 
At the end of World War II, the Soviets also entered northeastern China after the Yalta Conference in 1945, which allowed Soviet troops to march into Manchuria to fight the Japanese army. After the Soviet Union provided support to the Chinese Communist Party (CCP, 中國共產黨), the ROC also accused the Soviets of trespassing in Chinese territory to the UN in September 1949.  Both Iran and the ROC were united in their suspicions of the Soviets.
Iran’s Choice between China and Taiwan
From the beginning of the 1950s, Taiwan and Iran encountered several obstacles that shook their relationship. The PRC, established in October 1949, began to gain a growing number of diplomatic allies to the detriment of Taipei. Taiwan, at that time, was concerned about whether Iran would maintain their friendship. Since Iran had been the first Asian country to sign a treaty of friendship with the ROC, its position on China was considered a significant issue for Taipei.
In the meantime, the ROC’s representation in the UN was challenged by the Soviet representative to the UN, Yakov Malik, who did not recognize the ROC but rather supported the PRC.  There were also rumors that the Soviets asked Iran to recognize the PRC.  The Soviet Union withdrew its troops from Iran after 1946 and showed friendliness towards Iran, abandoning its past aggression and hostility. Although the United States wanted to approach Iran to provide economic and military assistance, Shah Pahlavi was aware that perhaps improving ties with the Soviets was more urgent than help from a distant country such as the United States. Under this context, Taipei desired to know Iran’s decision regarding their relationship.  In response, the Iranian government told ROC chargé d’affaires in Tehran, Hsu Shao-Chang (許紹昌), that they would support Taiwan and ROC representation in the UN.  In September 1954, the First Taiwan Strait Crisis broke out. President Chiang Kai-shek viewed this as an opportunity to make US President Dwight Eisenhower aware that Taiwan faced a worse situation than before and that American military assistance to Taiwan was urgently needed. 
In April 1955, Iran and China were invited to the Bandung Conference, which was attended by other Asian and African countries and organized by Indian Prime Minister Jawaharlal Nehru, who had recognized the PRC in 1950. The purpose of the conference was to fight against imperialist forces in the Cold War era.  ROC Ambassador in Tehran Tsai I-Tian (蔡以典) told the Iranian government that the Chinese Communist Party (CCP) would accrue political and diplomatic advantages from the Bandung Conference, and that Iran could only attend the conference once a truce was declared in the Taiwan Strait.  Eventually, the Iranian government decided to attend the conference, but stated that they would not violate any interests of Taiwan.  For Iran, joining the Bandung Conference was an opportunity to let the world know that Iran was a member of the family of nations. For Taiwan, however, it meant more uncertainty from its Asian friend.
Drifting Relations between Taiwan and Iran
After World War II and the start of the Cold War, Iran was careful to avoid joining the Western bloc that was aimed at containing Soviet expansion into the Indian Ocean and Middle East. From 1954 to 1955, Britain preferred to cooperate with Pakistan, Turkey, and Iraq—a relationship referred to as the Baghdad Pact—for the purpose of promoting anti-communism and isolating Egypt. In October 1955, Iran joined the Baghdad Pact. The Soviets claimed that the nature of the pact was not simply for regional cooperation, but also to counter communism. 
When Egypt tried to build closer relations with China in 1955, Iran, by contrast, was more concerned about maintaining good relations with the Soviets than with the Chinese. Subsequently, Egypt announced its recognition of China in May 1956, largely because Beijing had supported Egyptian independence at the Bandung Conference. The United States feared that Iran would possibly lean towards the Soviet Union as Egypt had previously done, especially when Shah Pahlavi decided to go to Moscow in 1956 to emphasize Iranian friendliness towards the Soviets. 
Following the Moscow visit, the ROC Ambassador in Tehran Wu Nan-ru (吳南如) sent a telegraph to Taipei, stating that Shah Pahlavi was satisfied with the trip, while the Soviets showed their hospitality.  It could be argued that the attitude of the Soviet Union towards Pahlavi’s visit was careful and serious. While it was perhaps difficult to make Iran an ally, the Soviets made sure that Iran at least did not join the American side. Ambassador Wu asserted that this was evidence of the Soviet’s “Smile Diplomacy” and expressed his fear that Iran would join the communist bloc and recognize the PRC soon. 
During this time period, it seemed that Iran did not necessarily favor Taiwan, particularly when it came to relations with the United States. In Mohammad Reza Pahlavi’s biography “Mission for My Country,” he argues that the United States had paid more attention to Taiwan than to Iran. He writes, “Taiwan has in the same period obtained about four times as much American military and non-military aid from America as has Iran. Admittedly Taiwan’s situation in the Far East is strategic, but I maintain that the Middle East ours is no less so.”  In the broader context of the Cold War competition—which was more severe in East Asia than in the Middle East—Taiwan earned more attention from the United States than Iran. Even the visit of Shah Pahlavi to Taiwan in 1958, in fact, did not signify that Iran and Taiwan had a close and durable relationship.
After the end of the Second World War, Iran and Taiwan faced the challenges posed by the Cold War. In the late 1940s, the two countries encountered immense pressure from communist countries. From the early 1950s, Taiwan was under threat from the PRC, while Iran was met with friendliness from the Soviet Union. During this period, Taiwan felt uncertainty and instability due to Iran’s desire to have good relations with both the United States and its northern neighbor the Soviet Union. Tehran expected help from the United States and also wished to be friendly with the Soviet Union. Once Iran had the opportunity to recognize the PRC—despite having good relations with the United States—and ultimately the ROC would lose Tehran’s support for maintaining its representation in the UN. The drift in relations between Tehran and Taipei during this period would foreshadow Iran’s eventual switch of formal recognition from the ROC to the PRC in 1971.
The main point: Between 1949 and 1956, the ROC and Iran, which had been allies since 1920, were under threat from communism. Yet, Taiwan could not secure its representation in the UN and faced military attacks by China, while Iran had an opportunity to join the international community.
 Li-Chiao Chen, “The Signing of the Sino-Iranian Treaty of 1920,” Iranian Studies 52, Nos. 5-6 (2019): 999-1008.
 Li-Chiao Chen, “China and Iran’s Efforts for Cooperation 1929-1946,” International Cooperation in China (Taipei: National Cheng Chi University Publisher, 2018), 226-227 (in Chinese).
 John W. Garver, China and Iran: Ancient Partners in a Post-Imperial World (Seattle and London: University of Washington Press, 2006), 171.
 Joan Beaumont, “Great Britain and the Rights of Neutral Countries: The Case of Iran, 1941,” Journal of Contemporary History, 16, No. 1 (1981): 214.
 J. C. Hurewitz, Diplomacy in the Near and Middle East: A Documentary Record: 1914-1956 (New York: D. Van Nostrand Company, 1956), 232-234.
 Jamil Hasanli, At the Dawn of the Cold War: The Soviet-American Crisis over Iranian Azerbaijan, 1941-1946 (Lanham: Rowman & Littlefield Publishers, 2006), 188-195.
 No. 641.0/0061, April 16, 1946, The Archives of the Institute of Modern History, Academia Sinica (中央研究院近代史研究所), 70.
 Tao-Chung, Hsiao, “Cold War and Diplomacy: The Republic of China’s Accusation Against the Soviet Union in the U.N., 1946-1952,” Fu Jen Historical Journal, 17, 2006: 471-515.
 Cheng-Hua Wang (ed), Documentary Collection on R.O.C. and United Nations: Chinese Representation (Hsin Tien: Academia Historica, 2001), 2.
 11-04-09-02-01-003, No. 105.22/33, January 19, 1951, The Archives of the Institute of Modern History, Academia Sinica (中央研究院近代史研究所), 1.
 No. 101.2/0001, September 2, 1953, The Archives of the Institute of Modern History, Academia Sinica (中央研究院近代史研究所), 126.
 Ali E. Hillal Dessouki, “Nasser and the Struggle for Independence,” in WM. Roger Louis and Roger Owen (eds), Suez 1956: The Crisis and its Consequences (Oxford: Clarendon Press, 1989), 33-35.
 林孝庭(Hsiao-tin Lin), 《台海、冷戰、蔣介石：1949-1988解密檔案中消失的臺灣史》（台北：聯經出版社, 2015）, 131-132.
 Naoko Shimazu, “Diplomacy As Theatre: Staging the Bandung Conference of 1955,” Modern Asian Studies, 48, No. 1 (2014): 225-231.
 No. 101.2/0001, February 7, 1955, The Archives of the Institute of Modern History, Academia Sinica (中央研究院近代史研究所), 159.
 No. 101.2/0001, April 7, 1955, The Archives of the Institute of Modern History, Academia Sinica (中央研究院近代史研究所), 165.
 11-30-16-02-053, October 14, 1955, The Archives of the Institute of Modern History, Academia Sinica (中央研究院近代史研究所), 105.
 11-30-16-02-053, April 10, 1956, The Archives of the Institute of Modern History, Academia Sinica (中央研究院近代史研究所), 121.
 11-30-16-02-053, July 14, 1956, The Archives of the Institute of Modern History, Academia Sinica (中央研究院近代史研究所), 137.
 11-30-16-02-053, November 6, 1956, The Archives of the Institute of Modern History, Academia Sinica (中央研究院近代史研究所), 155-156.
 Mohammad Reza Pahlavi, Mission for My Country (London: Hutchinson & Co., 1961), 314-315.