Yahya Muhammad Hamid ed-Din (or Imam Yahya) (18 June 1869 – 17 February 1948) became Imam of the Zaydis in 1904 after the death of his father, Muhammad Al-Mansur, and Imam of Yemen in 1918.
His name and title in full was "His majesty Amir al-Mumenin al-Mutawakkil 'Ala Allah Rab ul-Alamin Imam Yahya bin al-Mansur Bi'llah Muhammad Hamidaddin, Imam and Commander of the Faithful" (the prince of the believers, he who relies on God, the Lord of the Universe).
Yahya Muhammad Hamid ed-Din was born on Friday 18 June 1869 in Sanaa into the Hamidaddin branch of the al-Qasimi dynasty who ruled most of Yemen proper and South Saudi Arabia today for over 900 years.
Upon the death of his father in 1904, Yahya became Imam, effectively ruler over the mountainous areas of the future North Yemen.
However, the Ottomans who made claim on the area did not recognize the rule of the Imams of Yemen since their entry into Yemen.