This work surveys over 100 Yemeni astronomical manuscripts preserved in the libraries of Europe and the Near East. These sources attest to an active interest in mathematical astronomy in the Yemen from the 10th century to the early 20th century, and the writings of various Yemeni astronomers of the 13th and 14th centuries are particularly impressive. To the historian of Islamic science some of these works are of interest because they preserve earlier Iraqi and Egyptian astronomical sources which are no longer extant in their original form, and to the historian of Islamic institutions others are of interest because they cast new light on the astronomical orientation of the Kaba and on the early history of the institution of prayer in Islam.