October 16, AD 690

Wu Zetian

Wu Zhao proclaims the Zhou dynasty in place of Tang

She chose the Double Ninth festival to announce that Tang had become Zhou — and did not take the emperor's title until three days later.

The ninth day of the ninth month, 690

On the ninth day of the ninth lunar month — 16 October 690 — Wu Zhao proclaimed the dynastic change from Tang to Zhou, and changed the era name to Tianshou, "Heaven-granted."

She did not ascend a Tang throne that day. She replaced the dynasty with one of her own, conventionally called Wu Zhou to distinguish it from the ancient Zhou.

Three days to the title

The formal accession — the title "Holy and Divine Emperor," together with the demotion of her son Ruizong to imperial heir — followed on 19 October.

Popular timelines merge the two steps. Until the 19th, Ruizong formally retained imperial dignity.

The groundwork

The change had been argued for in advance: the official Fu Youyi led an earlier petition campaign urging that the state name be changed to Zhou.

A commentary on the Great Cloud Sutra, associated with Faming and Xue Huaiyi, presented Wu's rule as cosmically ordained and identified her with a prophesied Buddhist ruler.

The formal edict placing Buddhism above Daoism came later, in early 691.

Sources

Researched 23 Aug 2026 6 sources 2 audit passes

How this was checked

Researched from the web into a fact sheet, rewritten from that sheet, then audited against it by a different model. How the pipeline works →

What the sources leave uncertain

The date itself is secure, but sources distinguish two steps that popular timelines often merge: the Zhou dynastic proclamation on 16 October and Wu's formal imperial title and her son's demotion on 19 October.
'Wu Zetian' is the familiar posthumous name; during this event she was Wu Zhao, using the newly created form 曌.