Lusitanians
The Lusitani, who were Indo-European speakers, established themselves in the region in the 6th century BC, but historians and archeologists are still undecided about their ethnogenesis. Some modern authors consider them to be an indigenous people who were Celticized culturally and possibly also through intermarriage.
The archeologist Scarlat Lambrino defended the position that the Lusitanians were a tribal group of Celtic origin related to the Lusones (a tribe that inhabited the east of Iberia). Some have claimed that both tribes came from the Swiss mountains. Others argue that the evidence points to the Lusitanians being a native Iberian tribe, resulting from intermarriage between different local tribes.
The first area colonized by the Lusitani was probably the Douro valley and the region of Beira Alta (present day Portugal); in Beira, they stayed until they defeated the Celtici and other tribes, then they expanded to cover a territory that reached Estremadura before the arrival of the Romans.
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