The walled city of Saʿda (Ar. Ṣaʿda), the capital of North Yemen, was once an iron-mining and tanning center and an important station on the Himyarite Sanʿa–Mecca trade route. It is built on a plateau 2,300 meters (7,546 feet) high about 250 kilometers (155 miles) north of Sanʿa. When the Zaydi imām al-Hādī ilā al-Ḥaqq from northern Persia established the Zaydi state in northern Yemen in the tenth century, he chose Saʿda as its capital, and it became a center of Zaydi Shiʿite learning. Al-Hādī Mosque in Saʿda is still an important Zaydi Shiʿite educational institution.

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