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In the middle Priod of Islamic astronomy, the Mu’tabar Sanjar? Z?j was composed by the Iranian astronomer ‘Abd al-Rahm?n al-Kh?zin? (fl.475-525 A.H./1082-1130 A.D) who lived in Marw. In his introductin to his z?j he remarks that made observations for 35 years to prepare it, and he lists his innovations, especially in the field of lunar crescent visibility and in the theory of eclipse, then he demonstrates its superiority over pervious z?jes in general.
In this paper I present a summery of some important sections of this z?j, and I mention the extant mss. thereof. Of course each section will need a separate through study. Despaite its importance, the Sanjar? z?j has scarcely been considered in detail by modem science historians, and its whole text has not been published yet.