sentences:  The findings showed that the Varna culture had trade relations with distant lands, possibly including the lower Volga region and the Cyclades, perhaps exporting metal goods and salt from the Provadiya rock salt mine.The copper ore used in the artifacts originated from a Sredna Gora mine near Stara Zagora, and Mediterranean spondylus shells found in the graves may have served as primitive currency.Burials at Varna have some of the world's oldest gold jewelry.