"In 1727 the to-min or 'idle people' of Cheh Kiang province (a Ningpo name still existing), the yoh-hu or 'music people' of Shanxi province, the si-min or 'small people' of Kiang Su (Jiangsu) province, and the Tanka people or 'egg-people' of Canton (to this day the boat population there), were all freed from their social disabilities, and allowed to count as free men.  What does 'se-min' mean