Constance of Hungary, Queen of Galicia

King Bela IV had ten children. Constance's sisters were St. Kunegunda , married to the Kraków-Sandomir prince Boleslaw V the Chaste , Bl. Yolanda of Poland , married to Prince Bolesław the Pious of Kalisz, Anna of Hungary, married to the eternal rival of the Romanovychs for the Galician throne, Ban of Machva and Slavonia Rostislav Mikhailovich , Elizabeth of Hungary , married to Duke of Bavaria Henry XIII Wittelsbach, St. Margaret of Hungary, who lived a religious life since her birth. Her brother was the king Stephen V of Hungary.

Through the children of her sister Anna, the children of Constantia and Leo I were related to the main royal families of Central Europe. She is a descendant of the Grand Dukes of Kiev Vladimir II Monomakh and Yaroslav the Wise. Great-great-granddaughter of the Rus princess Euphrosyne of Kiev, daughter of the Grand Duke of Kiev Mstislav I the Great.

They had three children:

• Yuri I of Halych–Volhynia (24 April 1252/1257 – 18 March 1308).
• Sviatoslava Lvovna of Halych–Volhynia (died 1302), a nun
• Anastasia Lvovna of Halych–Volhynia (died 12 March 1335), who married Siemowit of Dobrzyń.