In 1368, the Ming dynasty's founding year, the first Ming emperor Hong Wu decreed that women of the common people who were widowed before the age of 30 and who remained chaste beyond the age of 50 should be publicly honored and their families freed from corvee service.
明洪武元年昭令天下：民間寡婦，三十歲以前亡夫守制，五十歲以後不改節者，旌表門閭，免除本家差役。