Conservation work inside the Iskandariyya madrasa of Zabid led to the unexpected exposure of an inscriptional panel next to the mihrab. The inscription was found not to have the expected religious content. Instead, the texts reflects the dedication of a waqf in 940/1533 in support of a madrasa which is to be sustained by the product of harvest derived from land in the Wadi Zabid district. The text lists canals and individual properties of land watered by them. Levies from the properties are given in dry measures for grain. Understanding the detailed textual information that the inscription gives on land and water allocation rights requires use of archaeological evidence of the irrigation infrastructure that was put into place in the Zabid hinterland during earlier centuries. Under the Rasulids in particular (1228-1454), personal interest of the rulers led to large-scale investment in irrigation schemes in the Wadi Zabid, the remains of which were the focus of several seasons of archaeological excavations. Matching the archaeological with the textual information also shows the mutual dependence of the city and its agricultural hinterland. Successful management of the irrigation system in the Wadi Zabid lay in the hands of the urban authorities. At the same time, the farmland was of fundamental importance for sustenance of Zabid's economic, cultural and religious life, not least as demonstrated by the waqf dedication in support of the madrasa.