Civil strife and foreign invasions, such as the Mongol invasions in 1240/1241, 1259/1260 and 1287/1288, weakened and depopulated many of the small Polish principalities, as the country was becoming progressively more subdivided.
Rahvarahutused ja välismaised sissetungid, nagu mongolite sissetungid aastatel 1240/1241, 1259/1260 ja 1287/1288, nõrgestasid ja tühjendasid paljusid väikeseid Poola vürstkondi, kui riik üha rohkem killustus.