In one corner of China, women invented a writing system men weren't meant to read

Nüshu developed among women in Jiangyong County, Hunan province, likely by the 19th century, at a time when girls were routinely denied formal literacy in standard Chinese characters. Women used the script to write letters, songs, and 'third-day missives' given to brides, often never teaching it to the men in their lives; the last fluent native user died in 2004, though the script is now taught to preserve it.

— Linguistic and ethnographic record, Nüshu — Jiangyong County, Hunan, China