Fig. 13 Climatic variations in Italy from the third millennium B.C.
As the network of cuniculi in Latium lies quite close to the surface and was fed by frequent rains, the local population could have pure drinking water without having to gather and store surface water.
An excavation of this type can only be explained by the presence of permanent settlements with a population engaged in, for that time, an advanced agriculture. This stage was reached in the area in question around the 9th century B.C. when the first urban communities flourished on the plain.5
The Etruscans had settled north of the Tiber River, the Latins to the south. It was the fusion of these two large ethnic groups that contributed to the creation of the conditions favourable to the birth of Rome. Cultural uniformity between Southern Etruria and ancient Latium had already been achieved in the 9th century B.C. with a steady increase in the rural population of the region.
It was in this environment that the technique of excavating cuniculi was born. At that time the continually increasing cultural exchanges with the Orient could also have affected the spread of cuniculi. But the direction of this exchange remains to be clarified.
From 300/200 B.C. onwards the average temperature increased and average rainfall decreased in the Mediterranean basin to such an extent that from the 1st century B.C. onwards the region became arid while the cuniculi excavated in the first millennium gradually dried up. Thermal conditions became favourable to the proliferation of the anofele mosquito on the plain made swampy by the water which ran off from the nearby mountains. Rural areas became so depopulated that traces of the many populated centres in pre-Roman Latium were lost. Only very recent archaeological excavations are bringing to light these lost villages. Cuniculi which were no longer being used were forgotten and no mention was made of them by the Roman authors. Only Tito Livio briefly mentioned them as military works.
5 The use of the term "plain" is not strictly speaking appropriate as it refers here to a land formation of the type pictured in Figure 3 which shows a undulated surface. The term "plain" is used here in contrast to "mountains"