As a generic term in Arabic and Persian, saw?d was used to denote the irrigated and cultivated areas in any district. Unmodified, it always referred to southern Iraq, the saw?d of Baghdad. It replaced the earlier and more narrow term R?dh?n.
Michele Campopiano, "Land Tax Al? l-misa and muq?sama: Legal Theory and Balance of Social Forces in Early Medieval Iraq (Sixth to Eighth Centuries)", in Journal of the Economic and Social History of the Orient, 54/2, 2011, 239-269 
^Hans Wehr (1979). saw?d. A Dictionary of Modern Written Arabic. Otto Harrassowitz Verlag. Retrieved 2019.