Please note that Mommsen uses the AUC chronology (Ab Urbe Condita), i.e. from the founding of the City of Rome. You can use this reference table to have the B.C. dates
From: The History of Rome, by Theodor Mommsen
Translated with the sanction of the author by William Purdie Dickson
Primitive Races of Italy
We have no information, not even a tradition, concerning the first migration of the human race into Italy. It was the universal belief of antiquity that in Italy, as well as elsewhere, the first population had sprung from the soil. We leave it to the province of the naturalist to decide the question of the origin of different races, and of the influence of climate in producing their diversities. In a historical point of view it is neither possible, nor is it of any importance, to determine whether the oldest recorded population of a country were autochthones or immigrants. But it is incumbent on the historical inquirer to bring to light the successive strata of population in the country of which he treats, in order to trace, from as remote an epoch as possible, the gradual progress of civilization to more perfect forms, and the suppression of races less capable of, or less advanced in, culture by nations of higher standing.
Italy is singularly poor in memorials of the primitive period, and presents in this respect a remarkable contrast to other fields of civilization. The results of German archaeological research lead to the conclusion that in England, France, the North of Germany and Scandinavia, before the settlement of the Indo-Germans in those lands, there must have dwelt, or rather roamed, a people, perhaps of Mongolian race, gaining their subsistence by hunting and fishing, making their implements of stone, clay, or bones, adorning themselves with the teeth of animals and with amber, but unacquainted with agriculture and the use of the metals. In India, in like manner, the Indo-Germanic settlers were preceded by a dark-coloured population less susceptible of culture.
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Reference address : https://www.ellopos.net/elpenor/rome/1-02-earliest-migrations-italy.asp