# Leszek II the Black becomes senior duke (1279)

URL: https://poland-history.com/timeline/1279-leszek-ii-the-black-becomes-senior-duke
Location: Kraków
Categories: ruler-change

Leszek the Black, Duke of Sieradz, inherited Kraków under the will of his uncle Bolesław V the Chaste. He defended it against Mongols, Lithuanians and rival dukes. Within the broader Fragmentation period: After 1138 Poland split into duchies ruled by rival Piast princes. Mongol invasions, German settlement, the growth of towns and the arrival of the Teutonic Knights reshaped the land before it was reunited. At this point in the timeline (1279), the governing authority was Leszek II the Black (High Duke of Poland). Duke of Sieradz and Kraków who repelled the Yotvingians and faced the third Mongol invasion. Leszek II the Black becomes senior duke mattered because succession and legitimacy shaped alliances, institutions and the direction of state policy. The event is placed here so readers can follow it alongside changes in government, warfare, society, religion and culture across Polish history.

## Why it matters
Leszek II the Black becomes senior duke mattered because succession and legitimacy shaped alliances, institutions and the direction of state policy.

Ruler at the time: [Leszek II the Black](https://poland-history.com/rulers/leszek-ii-the-black)

## Sources
- [Wikipedia — Leszek II the Black](https://en.wikipedia.org/wiki/Leszek_II_the_Black)
- [Encyclopaedia Britannica topic lookup — Leszek II the Black becomes senior duke](https://www.britannica.com/search?query=Leszek+II+the+Black+becomes+senior+duke)
- [Wikipedia — History of Poland during the Piast dynasty (period overview)](https://en.wikipedia.org/wiki/History_of_Poland_during_the_Piast_dynasty#Fragmentation_of_the_realm_(1138%E2%80%931320))