Union of Krewo
Jogaila weds Poland's queen, joining Lithuania and Poland

Under the 1385 agreement, Grand Duke Jogaila of Lithuania promised to become Catholic, marry Queen Jadwiga of Poland and join Lithuania to the Polish crown. In 1386 he was crowned Władysław II, founding the Jagiellonian dynasty.
Wikipedia (Russian) · Wikipedia (English) · 14th century
Meanwhile around the world (±25 years)
Eastern Europe & Russia
- 1380 Battle of Kulikovo — 5 years earlier
- 1410 Battle of Grunwald — 25 years later
Asia
- 1368 Founding of the Ming dynasty — 17 years earlier
- 1370 Timur makes Samarkand his capital — 15 years earlier
- 1377 Jikji, printed with movable metal type — 8 years earlier
- 1392 Founding of Joseon — 7 years later
- c. 1400 Founding of Malacca — 15 years later
Alive at the time
- Timur (aged 49)
- Sergius of Radonezh (aged 71)
- Murad I (aged 59)
- Ibn Khaldun (aged 53)
- Dmitry Donskoy (aged 35)
- Ashikaga Yoshimitsu (aged 27)
- Andrei Rublev (aged 25)
- Bayezid I the Thunderbolt (aged 25)
- Richard II (aged 18)
- Sigismund (aged 17)