The Ottomans had two fundamental interests to safeguard in Yemen: The Islamic holy cities of Mecca and Medina, and the trade route with India in spices and textiles—both threatened, and the latter virtually eclipsed, by the arrival of the Portuguese in the Indian Ocean and the Red Sea in the early 16th century. Hadım Suleiman Pasha, The Ottoman governor of Egypt, was ordered to command a fleet of 90 ships to conquer Yemen.
Imam al-Mutawakkil Yahya Sharaf ad-Din ruled over the northern highlands including Sana’a, while Aden was held by the last Tahiride Sultan ‘Amir ibn Dauod. Hadım Suleiman Pasha stormed Aden in 1538, killing its ruler, and extended Ottoman authority to include Zabid in 1539 and eventually Tihama in its entirety. Zabid became the administrative headquarters of Yemen Eyalet. The Ottoman governors did not exercise much control over the highlands. They held sway mainly in the southern coastal region, particularly around Zabid, Mocha, and Aden. Of 80,000 soldiers sent to Yemen from Egypt between 1539 and 1547, only 7,000 survived.
The Ottomans sent yet another expeditionary force to Zabid in 1547, while Imam al-Mutawakkil Yahya Sharaf ad-Din was ruling the highlands independently. Imam al-Mutawakkil Yahya chose his son Ali to succeed him, a decision that infuriated his other son al-Mutahhar ibn Yahya. Al-Mutahhar was lame, so he was not qualified for the imamate. He urged Oais Pasha, the Ottoman colonial governor in Zabid, to attack his father. Indeed, Ottoman troops supported by tribal forces loyal to Imam al-Mutahhar stormed Taiz and marched north toward Sana’a in August 1547. The Turks officially made Imam al-Mutahhar a Sanjak-bey with authority over ‘Amran. Imam al-Mutahhar assassinated the Ottoman colonial governor and recaptured Sana’a, but the Ottomans, led by Özdemir Pasha, forced al-Mutahhar to retreat to his fortress in Thula. Özdemir Pasha effectively put Yemen under Ottoman rule between 1552 and 1560. He was considered a competent ruler given Yemen’s notorious lawlessness, garrisoning the main cities, building new fortresses, and rendering secure the main routes. Özdemir died in Sana’a in 1561 and was succeeded by Mahmud Pasha.