The Crisis of the Piast dynasty[citation needed] was a period of constant wars, invasions and rebellions, lasting from the death of Bolesław the Brave in 1025 until the reunification of the Polish lands by Casimir the Restorer.

During the crisis, Poland suffered very severe material and demographic losses, the Polish capital Gniezno was completely destroyed, Lusatia and Milsko were taken over by the Germans, Bełz by Kievan Rus and Moravia and initially Silesia by Bohemia.

Independent since about 1005, pagan Western Pomerania, Prussia and Polabia, remembering Bolesław's attempts to seize them, were also hostile to Christian Poland, so Mieszko had enemies himself on all borders.

In addition to the brothers mentioned earlier who were jealous of the throne, there was also a growing class of magnates, reluctant to have a strong central authority, over the pagan population imposed from above by the ecclesiastical institutions managed at the time largely by foreigners who did not speak the native language.

Despite the problems, however, Mieszko tried to continue the policy of Bolesław, meddling in the internal affairs of the Holy Roman Empire, establishing cooperation with the opposition there, thus emphasizing his independence.

Mieszko II obtained the help of Count Siegfried, son of the Margrave of the Eastern March Odo, in the fighting.

In October 1028, their envoy arrived at the state convention in Pöhlde, asking the emperor for protection from Mieszko II's incursions and promising support in the fight against the Polish ruler.

While Mieszko II was busy defending Lusatia in the west, an armed expedition was coming from the east, led by Yaroslav the Wise and Mstislav the Brave, supported by the future Norwegian king Harald III.

As a result of losing the war, Poland lost the territories of Lusatia, Milsko to Germany, Cherven Cities to Kievan Rus and probably Moravia to Bohemia and Slovakia to Hungary.

After the death of Otto and Bezprym, he reunited the state in 1033, but failed to regain the crown or restore stable structures of monarchical power.

While tribal-wide cults were eliminated easily, sacred and magical forms of family life were deeply rooted in consciousness and culture.

According to the historian Gerard Labuda, it is possible that some group of pagan priests led by Bolesław the Forgotten, operating underground, took advantage of the discontent of the population and pointed out as the enemy - the God of the Christians.

Some historians suggest that "abandonment of the Christian faith" played a secondary role in the uprisings, and their purpose was to fight against the exploitation of the magnates, including the clergy, and state institutions.

According to surviving accounts, in 1038, when the Czechs entered riot-stricken Poland, they found the temples of Krakow, Gniezno and other cities intact.

Seizing the opportunity, around 1038,Miecław, the king's cup-bearer, declared the independence of his own state in Masovia from the rest of Poland, and started his own royal dynasty.

It probably erupted in 1038 and was a reaction to the imposition of heavy burdens on the population, which it had to bear for the benefit of the state, the magnates and the Catholic Church.

After the period of confusion following the Ruthenian invasion and the weakening of monarchical power, the state was no longer able to suppress the discontent of the population, which found an outlet in an uprising directed against the magnates and Christianity.

Supporters of the pre-Christian religion found a wide and positive public resonance, especially since Christianity in Poland at that time was very young and superficial.

...slaves rose up against the masters, liberators against the noble-born, elevating themselves to the government, and kept some of them in captivity in reverse, killed others, and married their wives in a bawdy manner and criminally shredded the eminence (...).

...And there was a great destruction in the Polish lands, and having arisen, the people killed the bishops and priests and their lords...The unrest bypassed only Mazovia, where Mieszko II's former heir-apparent Miecław (Masław) proclaimed himself prince.

The booty of the Czechs in Gniezno also included a gold cross donated by Mieszko I, golden tablets set with jewels and many other valuables.

In addition, Bohemian soldiers demolished the religious buildings in Poznan that had been erected by Mieszko I to celebrate the baptism of Poland, and ransacked the tomb of that ruler.

[8][7] As Gall Anonymous wrote: "And so long did the said towns remain abandoned, that in the church of St. Adalbert the Martyr and St. Peter the Apostle wild animals found lairs."

From Giecz, whose population surrendered without a fight, Bretislav resettled numerous craftsmen to Bohemia, to a place henceforth called Hedčany.

[9] In addition, he received help from Yaroslav the Wise, prince of Kievan Rus, who also did not want to allow permanent anarchy to prevail in Poland.

The battle ended with a decisive Polish victory and the destruction of Miecław's army and led to the signing of a truce between both sides.

This prompted a complaint from Bretislav I to Emperor Henry, which led to a congress at Goslar in November of the same year, at which Casimir averted the threat of German intervention.

In 1051 Casimir supported Emperor Henry in an expedition against Andrew I of Hungary, during which Polish troops took part in the Battle of Rabanica.

Instead of maintaining a permanent troop of warriors, he initiated the custom of granting land to knights in exchange for military service.

During his long reign, which lasted eighteen years, he led the restoration of Polish statehood and regained for the Piasts the state within such boundaries as he had received from Mieszko II Lambert.