The Urnfield culture might have brought proto-Italic people from among the "Italo-Celtic" tribes who remained in Hungary into Italy. These tribes are thought to have penetrated Italy from the east during the late second millennium BC through the Proto-Villanovan culture. They later crossed the Apennine Mountains and settled central Italy, including Latium. Before 1000 BCE several Italic tribes had probably entered Italy. These divided into various groups and gradually came to occupy central Italy and southern Italy. This period was characterized by widespread upheaval in the Mediterranean, including the emergence of the Sea Peoples and the Late Bronze Age collapse. The Proto-Villanovan culture dominated the peninsula and replaced the preceding Apennine culture. The Proto-Villanovans practiced cremation and buried the ashes of their dead in Urnfield-style double-cone shaped funerary urns, often decorated with geometric designs. Elite graves containing jewellery, bronze armour and horse harness fittings were separated from ordinary graves, showing for the first time the development of a highly hierarchical society, so characteristic of Indo-European cultures. The burial characteristics relate the Proto-Villanovan culture to the Central European Urnfield culture and Celtic Hallstatt culture that succeeded it. It is not possible to tell these apart in their earlier stages. Generally speaking, Proto-Villanovan settlements have been found in almost the whole Italian peninsula from Veneto to eastern Sicily, although they were most numerous in the northern-central part of Italy. The most important settlements excavated are those of Frattesina in Veneto region, Bismantova in Emilia-Romagna and near the Monti della Tolfa, north of Rome. Various authors, such as Marija Gimbutas, associated this culture with the arrival, or the spread, of the proto-Italics into the Italian peninsula. In the 13th century BCE, Proto-Celts (probably the ancestors of the Lepontii people), coming from the area of modern-day Switzerland, eastern France and south-western Germany (RSFO Urnfield group), entered Northern Italy (Lombardy and eastern Piedmont), starting the Canegrate culture, who not long time after, merging with the indigenous Ligurians, produced the mixed Golasecca culture. Iron Age In the early Iron Age, the relatively homogeneous Proto-Villanovan culture (1200-900 BCE), closely associated with the Celtic Halstatt culture of Alpine Austria, characterised by the introduction of iron-working and the practice of cremation coupled with the burial of ashes in distinctive pottery, shows a process of fragmentation and regionalisation. In Tuscany and in part of Emilia-Romagna, Latium and Campania, the Proto-Villanovan culture was followed by the Villanovan culture. The earliest remains