Iron metallurgy and smithing were the most important branches of local industry. An example of highly developed tool production are asymmetrical plowshares. There is no sign of silver, gold, copper or lead mines in Moravia, but jewellery and weapons were produced locally. Accordingly, their prime material was acquired as loot or gift or brought to Moravia by merchants. Archaeological research also evidences the import of prestige goods, including silk, brocade and glass vessels. According to Štefan and Macháček, the Moravians primarily provided slaves, acquired as prisoners of war during their raids in the neighbouring regions, in exchange for these luxury goods. For instance, Archbishop Thietmar of Salzburg accused the Moravians of "bringing noble men and honest women into slavery" during their campaigns in Pannonia. Slave trading is also well documented: the "First Legend of Naum" narrates that many of Methodius's disciples "were sold for money to the Jews" after 885, and the "Raffelstetten Customs Regulations" makes mention of slaves delivered from Moravia to the west.