The region around Zwickau was settled by Slavs as early as the 7th century AD. The name Zwickau is probably a Germanization of the Sorbian toponym "Šwikawa", which derives from Svarozič, the Slavic Sun and fire god. In the 10th century, German settlers began arriving and the native Slavs were Christianized. A trading place known as "terretorio Zcwickaw"(in Medieval Latin) was mentioned in 1118. The settlement received a town charter in 1212, and hosted Franciscans and Cistercians during the 13th century. Zwickau was a free imperial city from 1290–1323, but was subsequently granted to the Margraviate of Meissen. Although regional mining began in 1316, extensive mining increased with the discovery of silver in the Schneeberg in 1470. Because of the silver ore deposits in the Erzgebirge, Zwickau developed in the 15th and 16th centuries and grew to be an important economic and cultural centre of Saxony.