For example:
king Władysław IV (9 June 1595 – 20 May 1648)
en.wikipedia.org/wiki/Władysław_IV_Vasa#Royal_titles
In Latin: "Vladislaus Quartus Dei gratia rex Poloniae, magnus dux Lithuaniae, Russiae, Prussiae, Masoviae, Samogitiae, Livoniaeque, necnon Suecorum, Gothorum Vandalorumque haereditarius rex, electus magnus dux Moschoviae."
In English: "Władysław IV, by grace of God the King of Poland, Grand Duke of Lithuania, Ruthenia, Prussia, Masovia, Samogitia, Livonia, and King of the Swedes, hereditary king of Goths and Vandals, elected Grand Duke of Muscovy."
king John II Casimir (22 March 1609 – 16 December 1672)
en.wikipedia.org/wiki/John_II_Casimir_Vasa#Royal_titles
in Latin: Ioannes Casimirus, Dei Gratia rex Poloniae, magnus dux Lithuaniae, Russie, Prussiae, Masoviae, Samogitiae, Livoniae, Smolenscie, Severiae, Czernichoviaeque; nec non-Suecorum, Gothorum, Vandalorumque haereditarius rex, etc.
English translation: John Casimir, by God's grace King of Poland, Grand Duke of Lithuania, Ruthenia, Prussia, Masovia, Samogitia, Livonia, Smolensk, Severia and, Chernihiv; and also hereditary King of the Swedes, Goths and Vandals.
There are many well known medieval sources which call medieval Poles - Vandals.