The popularity of great seal script (大篆, daiten) was further enhanced by political unrest and domestic wars between kingdoms. After the ruler of the Qin (秦) monarchy conquered the eight nations in 221 B.C., and united them under the name Qin Shi Huang (秦始皇, lit. the first Qin emperor), he introduced numerous political and legal reforms, including reforming the writing system, which were executed by Prime Minister Li Si (李斯). Over 3300 kanji were normalized in a small and vertically rectangular form of shouten (小篆, small seal script), leading further to creating the first Chinese dictionary of characters, The Erya (爾雅).
Small seal script was, however, neither an invention of one man, nor was it developed immediately. Roots of alteration that eventually led to unifying the great seal script go back long before 221 B.C., to the north-western territories of the Qin monarchy.
Aside from small seal script, there were seven other styles that coexisted during the Qin dynasty (including great seal script and clerical script – 隷書、reisho). Nonetheless, shouten was meant to be used as an official writing system. All eight styles that matured through the Han dynasty (漢朝, 221 B.C. – 206 C.E.) were known as Ba Ti (八體, “eight bodies”), although only few of them played a vital role, especially seal and clerical scripts. At the beginning, the latter was only used for everyday purposes and minor records. The eight scripts (as defined by Xu Shen (許慎, 58 C.E. – 147 C.E); a Chinese philologist of the Han dynasty) were: great seal script (大篆, daiten), small seal script (小篆, shouten), clerical script (隷書, reisho), courier voucher script (刻符, Chinese: ke fu), worm script (蟲書, Chinese: chong shu), script used for seals (摹印, Chinese: mo yin), script for ornamental tablets (署書, Chinese: shu shu) and script for inscriptions on weapons (殳書, Chinese: shu shu).
During the Eastern Han (東漢, 25–220 C.E.) clerical script (隷書, lit. “slave script”, as it was originally secondary to seal script, and mainly used by petty clerks) became the official style.
Seal script remained popular through the Han dynasty, preserved on numerous stone stelae (inscribed stone slabs), used for official documents and ceremonial purposes, inscriptions on bronze vessels, and seal carving (篆刻, tenkoku).
It is also being practiced in the modern era, not only in calligraphy (calligrapher seals, so called hanko, 判子) but also in business. All corporate and governmental offices use seals carved in seal script.