The most famous archaeological find from the prehistory and protohistory of Poland is the Biskupin fortified settlement (now reconstructed as an open-air museum), dating from the Lusatian culture of the early Iron Age, around 700 BC. The Slavic groups who would form Poland migrated to these areas in the second half of the 5th century AD. Up until the creation of Mieszko's state and his subsequent conversion to Christianity in 966 AD, the main religion of Slavic tribes that inhabited the geographical area of present-day Poland was Slavic paganism. After the Baptism of Poland the new religion accepted by the Polish ruler was Catholicism. The transition to Christianity was not a smooth and instantaneous process for the rest of the population as evident from the pagan reaction of the 1030s.