Rus'

More precisely - Kievan Rus'

Kievan Rus' was a loose federation in Eastern Europe and Northern Europe from the late 9th to the mid-13th century. Encompassing a variety of peoples, including East Slavic, Norse, Baltic, and Finnic. It was ruled by the Rurik dynasty. The modern nations of Belarus, Russia, and Ukraine all claim Kievan Rus' as their cultural ancestors, with Belarus and Russia deriving their names from it. At its greatest extent in the mid-11th century, Kievan Rus' stretched from the White Sea in the north to the Black Sea in the south and from the headwaters of the Vistula in the west to the Taman Peninsula in the east, uniting many East Slavic tribes.

Duchess Alexandra

Alexandra of Lithuania, Duchess consort of Masovia

Alexandra was the youngest daughter of Algirdas, Grand Duke of Lithuania, and his second wife, Uliana of Tver. Though Alexandra's exact date of birth is not known, it is thought that she was born in the late 1360s or early 1370s. In 1387, she married Siemowit IV, Duke of Masovia, and bore him thirteen children.

Queen Jadwiga

Queen Jadwiga of Poland (1373 or 1374 – 17 July 1399) also known as Hedwig, was the first female monarch of the Kingdom of Poland, reigning from 16 October 1384 until her death. She was the youngest daughter of Louis the Great, King of Hungary and Poland, and his wife Elizabeth of Bosnia. Jadwiga was a member of the Capetian House of Anjou, but she had more close forebears among the Polish Piasts. In 1997 she was canonized by the Catholic Church.

Jadwiga was crowned "king" in Poland's capital, Kraków, on 16 October 1384. With her mother's consent, Jadwiga's advisors opened negotiations with Jogaila, Grand Duke of Lithuania, who was still a pagan, concerning his potential marriage to Jadwiga. 

Jogaila signed the Union of Krewo, pledging to convert to Catholicism and to promote his pagan subjects' conversion. Jogaila, who took the baptismal name Władysław, married Jadwiga on 15 February 1386. Legend says that she had agreed to marrying him only after lengthy prayer, seeking divine inspiration.