The history of Plovdiv spans more than eight millennia. Numerous nations have left their traces on the cultural layers of the city. The earliest signs of habitation in the territory of Plovdiv date as far back as the 6th millennium BCE. Plovdiv has settlement traces including necropolises dating from the Neolithic era (roughly 6000–5000 BCE) like the mounds Yasa Tepe 1 in the Philipovo district and Yasa Tepe 2 in Lauta park. Archaeologists have discovered fine pottery and objects of everyday life on Nebet Tepe from as early as the Chalcolithic era, showing that at the end of the 4th millennium BCE, there was already an established settlement there which was continuously inhabited since then. Thracian necropolises dating back to the 2nd–3rd millennium BCE have been discovered, while the Thracian town was established between the 2nd and the 1st millennium BCE.