=3.= NORTHERN ITALY lies between the Swiss Alps and the Upper Apennines, and is almost covered by the great plain of the Po, which is one of the most fertile regions of Europe. It comprised, in the most ancient times, the three countries of Ligu´ria, Upper Etruria, and Vene´tia. The second of these divisions, together with some portions of the Ligurian and Venetian territories, was conquered, in the sixth century before Christ, by a Celtic population from the north and west, and was thenceforth known as Cisalpine Gaul. The region north of the Apennines does not belong to Roman or even Italian history until about the time of the Christian Era, when it became incorporated in the territories of Rome. =4.= The peninsula proper is divided into the two regions of central and southern Italy, by a line drawn from the mouth of the Tifer´nus, on the Adriatic, to that of the Sil´arus, on the western coast. CENTRAL ITALY comprised six countries, of which three, Etruria, La´tium, and Campania, were on the Tyrrhenian Sea, and three others, Um´bria, Pice´num, and the Sabine country, on the Adriatic. _Etruria_ was, in the earliest times, the most important division of Italy proper. It was separated from Liguria by the river Macra; from Cisalpine Gaul, by the Apennines; and from Umbria, the Sabine territory, and Latium, by the Tiber. _Latium_, lying south of Etruria, was chiefly a low plain; but its surface was varied by spurs of the Apennines on the north, and by the Vol´scian and Alban ranges of volcanic origin in the center and south. It included the Roman Campagna, now a solitary and almost treeless expanse, considered uninhabitable from the noxious exhalations of the soil, but during and before the flourishing period of Rome, the site of many populous cities. Several foreign tribes occupied portions of the Latin territory, among whom the Volsci, on the mountains which bear their name, and the Æqui, north of Prænes´te, were best worthy of mention. In the view of history, a cluster of low hills—seven east and three west of the Tiber—which constitute in later ages the site of Rome, is not only the most important part of Latium, but that which gives its significance to all the rest. =5.= _Campania_ was a fertile and delightful region, extending from the Liris to the Silarus, and from the Apennines to the sea. Greek and Roman writers never wearied of celebrating the excellence of its harbors, the beauty of its landscape, the exuberant richness of its soil, and the enchanting softness of its air. The coast is varied by the isolated cone of Vesu´vius and a range of volcanic hills, including the now extinct crater of Solfata´ra. _Umbria_ was a mountainous country east of Etruria. Before the coming of the Gauls, it extended northward to the Ru´bicon and eastward to the Adriatic; but its coast was wholly conquered by that people, who drove the Umbrians beyond the mountains.