Some scholars such as Edwin G. Pulleyblank, however, are unconvinced by the matriarchy theory of Chinese surnames due to a lack of independent evidence. An alternative hypothesis has been proposed, suggesting that the use of female radical in "xing" may have arisen from the clan exogamy system used during the Zhou dynasty (the words "xing" and "shi" also did not exist in the Shang dynasty oracle bones). In ancient times, people of the same "xing" were not permitted to marry each other and a woman married into an aristocratic clan needed to be of a different name. Based on observation of the evolution of characters in oracular scripture from the Shang dynasty through the Zhou: the 女 radical seems to appear during the Zhou period next to Shang sinograms indicating an ethnic group or a tribe. This combination seems to designate specifically a female and could mean "lady of such or such clan". The structure of the "xing" sinogram could reflect the fact that in the royal court of Zhou, at least in the beginning, only females (wives married into the Zhou family from other clans) were called by their birth clan name, while the men were usually designated by their title or fief.