The Qin script—as exemplified in bronze inscriptions prior to unification—had evolved organically from the Zhou script starting in the Spring and Autumn period. Beginning around the Warring States period, it became vertically elongated with a regular appearance. This was the period of maturation for the small seal script. It was systematized by prime minister
Li Si during the reign of Qin Shi Huang through the elimination of most character variants, and was imposed as the imperial standard. Through Chinese commentaries, it is known that Li Si compiled the '''', a partially-extant wordbook listing some 3,300
Chinese characters in the small seal script. Their form is characterized by being less rectangular and more squarish. In the popular history of Chinese characters, the small seal script is traditionally considered to be ancestral to
clerical script, which in turn prefigured every other script in use today. However, recent archaeological discoveries and scholarship have led some scholars to conclude that the direct ancestor of clerical script was proto-clerical script, which in turn evolved out of the lesser-known
vulgar or
popular writing of the late Warring States to Qin period. The first known
character dictionary was the 3rd-century BC '
, collated and referenced by Liu Xiang and his son Liu Xin; it is no longer extant. Not long after, the ' () was written by
Xu Shen. The
Shuowens 9,353 entries reproduce the standardized small seal forms for each entry, organized under 540
radicals. File:Edict bronze plate on iron standard weight Qin dynasty Shangtong.jpg|Small seal inscription on a Qin standard prototype weight—made from iron, and unearthed at
Wendeng,
Shandong in 1973 File:BronzePlaque-EdictOfSecondEmperor-Qin-ROM-May8-08.png|Edict of
Qin Er Shi in seal script. In the popular history of Chinese characters, the small seal script is traditionally considered to be the ancestor of
clerical script == Computer encoding ==