Neanderthal remains dating to around 150,000 years ago, or the Middle Paleolithic, are some of the earliest traces of human activity in the lands of modern Bulgaria.  Remains from ''Homo sapiens'' found there are dated ''c.'' 47,000 years BP.  This result represents the earliest arrival of modern humans in Europe. The Karanovo culture arose circa 6,500 BC and was one of several Neolithic societies in the region that thrived on agriculture. The Copper Age Varna culture (fifth millennium BC) is credited with inventing gold metallurgy. The associated Varna Necropolis treasure contains the oldest golden jewellery in the world with an approximate age of over 6,000 years. The treasure has been valuable for understanding social hierarchy and stratification in the earliest European societies.