The Kingdom of Yemen (Arabic: المملكة اليمنية, romanized: al-Mamlakah al-Yamanīyah), officially the Mutawakkilite Kingdom of Yemen (Arabic: المملكة المتوكلية اليمنية, romanized: al-Mamlakah al-Mutawakkilīyah al-Yamanīyah) and also known simply as Yemen or, retrospectively, as North Yemen, was a state that existed between 1918 and 1970 in the northwestern part of the modern country of Yemen. Located in the Middle East, the Kingdom of Yemen had an area of 195,000 km. The country was bordered by Saudi Arabia to the north, the Aden Protectorate to the south, and the Red Sea to the west. Its capital was Sanaa from 1918 to 1948, then Taiz from 1948 to 1962. Yemen was admitted to the United Nations on 30 September 1947. A republican coup was launched against the government in 1962, leading to the North Yemen Civil War. The royalist government only controlled the northern portions of the country from 1962 to 1970, until a peace deal in 1970 saw it largely dissolved.
Three days after the Ottoman Empire's decision to withdraw from Yemen following the 1918 Armistice of Mudros, Imam Yahya, the religious leader of the region, entered Sana'a and declared himself the ruler of Yemen. After declaring his rule, he launched attacks on Aden, which was under the auspices of the British Empire, but the British repelled the attacks. He then suppressed the rebellions of the tribes in Southern Tihama, advanced towards the Emirate of Asir, and increased his legitimacy by making agreements with the Kingdom of Italy and the Soviet Union. In 1927, he again attacked the countries under the auspices of the British Empire, and these attacks also failed. In 1934, he signed a friendship treaty with the United Kingdom, promising not to attack Aden in exchange for border negotiations. The Saudi-Yemeni war broke out because he did not accept to surrender the Emir of Asir, who was loyal to Saudi Arabia at that time and rebelled. Four months later, Yemen made peace by giving Jizan, Najran, and Asir to Saudi Arabia. After this war, the Kingdom of Yemen began to pursue an isolationist policy.
