What is the name of the ancient Chinese writing system found on oracle bones?

The ancient Chinese writing system found on oracle bones is called oracle bone script. It is the oldest attested form of written Chinese and dates mainly to the late second millennium BCE, especially the Late Shang period.

Scribes carved characters onto the shoulder blades of oxen and the plastrons, or undershells, of turtles. These objects were used in royal divination: heat produced cracks, and specialists interpreted the patterns before recording questions and results. The inscriptions concern warfare, sacrifices, agriculture, weather, illness, childbirth, and the Shang royal family.

Although many characters look pictorial, oracle bone script was already a mature writing system capable of recording Old Chinese, not merely isolated symbols or rough pictures. Its forms are the direct ancestors of later Chinese writing styles, including bronze inscriptions, seal script, clerical script, and regular script.

The script is sometimes called “shell-and-bone script,” from the Chinese term jiǎgǔwén. Kaishu is the later regular script, clerical script developed afterward, and seal script belongs to a later stage of the writing tradition. None of those names is the correct label for the Shang inscriptions themselves.