匈波之间的良好关系能追溯到中世纪时期。波兰和匈牙利的贵族家族(比如波兰的皮雅斯特王朝和匈牙利的阿尔帕德家族)之间经常通婚。拉約什一世自1342年开始兼任匈牙利和克羅埃西亞王國的国王,从1370年开始又兼任波兰国王,直至其于1382年去世为止。拉约什一世同时是其父安茹-西西里家族(house of Anjou-sicily)的查理一世的继承人和其舅父卡齐米日三世(波兰国王,皮雅斯特王朝的末代君主)的继承人。卡齐米日三世没有正式的男性后代作为其合法继承人。显然,卡齐米日三世为确保王室血统的延续并避免造成混乱,将其外甥匈牙利的拉约什一世立为其波兰王位的继承人。拉约什一世死后,其小女儿雅德维加接过了波兰的王座,并在后来成为了波兰历史上最为家喻户晓的君主之一。匈波两国在15世纪时又曾短暂地共有过同一位君主,即波兰雅盖隆王朝的瓦迪斯瓦夫三世·雅盖隆契克,但他在瓦尔纳战役与奥斯曼帝国的交战中阵亡,年仅20岁。在16世纪,波兰将匈牙利贵族巴托里·斯特凡选为其国王,后世认为巴托里是波兰历史上最伟大的统治者之一。
^Józef Kasparek, "Poland's 1938 Covert Operations in Ruthenia", East European Quarterly", vol. XXIII, no. 3 (September 1989), pp. 366-67, 370. Józef Kasparek, Przepust karpacki: tajna akcja polskiego wywiadu (The Carpathian Bridge: a Covert Polish Intelligence Operation), p. 11.
^Józef Kasparek, "Poland's 1938 Covert Operations in Ruthenia", p. 366.
^On 17 September 1939, pursuant to the Molotov–Ribbentrop Pact, the Soviet Union entered and took control of eastern Poland, including southeastern Poland. That former southeastern part of Poland now comprises western Ukraine.
^Józef Kasparek, "Poland's 1938 Covert Operations in Ruthenia", pp. 370-71.
^Józef Kasparek, "Poland's 1938 Covert Operations in Ruthenia", p. 370.
^Józef Kasparek, "Poland's 1938 Covert Operations in Ruthenia," pp. 371–73;Józef Kasparek, Przepust karpacki (The Carpathian Bridge); and Edmund Charaszkiewicz, "Referat o działaniach dywersyjnych na Rusi Karpackiej" ("Report on Covert Operations in Carpathian Rus").