Casimir I the Restorer
The first settlers were probably from the Celtic tribes. In later years they were driven out by the West Slavic or Lechitic clans. The importance of mining deposits arose after the capital of Poland was moved from Gniezno to Kraków by Casimir I the Restorer in the 11th century. However, further development of the mining practices was abruptly halted by the Mongol invasion, which destroyed Kraków and its surroundings in the 13th century. The area was subsequently populated with migrating Germans, who called the settlement "Gross Salz" (English: Grand/Great Salt) and from which the old Polish name "Wielka Sól" was derived. With time, the name evolved into Wieliczka, although the name Wielka Sól remained in official use, particularly in royal seals and documents.