Cymburgis of Masovia,, also Zimburgis or Cimburga, a member of the Polish Piast dynasty, was Duchess of Austria from 1412 until 1424, by her marriage with the Habsburg duke Ernest the Iron. As the mother of later Emperor Frederick III, Cymburgis, after Gertrude of Hohenberg, became the second female ancestor of all later Habsburgs, as only her husband's Ernestine branch of the family survived in the male line. Wikipedia