Near the end of the 6th millennium BC, the Kongemose culture was replaced by the Ertebølle culture in the south. During the 5th millennium BC, the Ertebølle people learned pottery from neighbouring tribes in the south, who had begun to cultivate the land and keep animals. They too started to cultivate the land, and by 3000 BC they became part of the megalithic Funnelbeaker culture. During the 4th millennium BC, these Funnelbeaker tribes expanded into Sweden up to Uppland. The Nøstvet and Lihult tribes learnt new technology from the advancing farmers (but not agriculture) and became the Pitted Ware cultures towards the end of the 4th millennium BC. These Pitted Ware tribes halted the advance of the farmers and pushed them south into southwestern Sweden, but some say that the farmers were not killed or chased away, but that they voluntarily joined the Pitted Ware culture and became part of them. At least one settlement appears to be mixed, the Alvastra pile-dwelling. It is not known what language these early Scandinavians spoke, but towards the end of the 3rd millennium BC, they were overrun by new tribes who many scholars think spoke Proto-Indo-European, the Battle-Axe culture. This new people advanced up to Uppland and the Oslofjord, and they probably provided the language that was the ancestor of the modern Scandinavian languages. They were cattle herders, and with them most of southern Scandinavia entered the Neolithic. Even though Scandinavians joined the European Bronze Age cultures fairly late through trade, Scandinavian sites present rich and well-preserved objects made of wool, wood and imported Central European bronze and gold. During this period Scandinavia gave rise to the first known advanced civilization in this area following the Nordic Stone Age. The Scandinavians adopted many central European and Mediterranean symbols at the same time that they created new styles and objects. Mycenaean Greece, the Villanovan Culture, Phoenicia and Ancient Egypt have all been identified as possible sources of influence in Scandinavian artwork from this period. The foreign influence is believed to originate with amber trade, and amber found in Mycenaean graves from this period originates from the Baltic Sea. Several petroglyphs depict ships, and the large stone formations known as stone ships indicate that shipping played an important role in the culture. Several petroglyphs depict ships which could possibly be Mediterranean.