Many of the results presented here are from the Oriental Institute Project for the History of Yemeni Terraced Agriculture. We are grateful to the National Science Foundation, the National Geographic Society, the American Institute for Yemeni Studies and private donors for financial contributions. We particularly thank Dr. Yusuf Abdullah, Ahmed Shemsan and Ali Sanabani of the General Organization of Antiquities and Museums, at Sana, as well as Christopher Edens, David Warburton, Marta Colburn, Nohar Sadek and the American Institute of Yemeni Studies for help and advice during fieldwork.