For we now have to leave the religion of the household, and to study that of the earliest form of the City-state. We have enjoyed a glint of light reflected from later times on the religion of the early Roman family, and are about to enjoy another glint--nay, a gleam of real light, and not merely a reflected one--which the earliest religious document we possess casts on the religion of the City-state of Rome. Between the two there is a long period of almost complete darkness. We know hardly anything as yet, and it is not likely that we shall ever know anything definite, about the stages of development which must have been passed before Rome became the so-called city of the Four Regions, when her history may be said really to begin. The pagus hardly helps us here; it was not an essential advance on the family, and its religion was comprehensive, not intensive. Each pagus, however, seems to have had within its bounds an _oppidum_, or stronghold on a hill; and such oppida were the seven _montes_ of early Rome, which, with the pagi belonging to them, survived in name to the end of the Republic, with some kind of a religious festival uniting them together, about which we have hardly any knowledge.[185] This looks like a stage in the process of change from farm to city, and it has generally been believed to mark one. Unfortunately nothing to our purpose can be founded on it. We must be content with the undoubted fact that about the eighth or seventh century B.C. the site of Rome was occupied and strengthened as a bulwark against the Etruscan people who were pressing down from the north upon the valley of the Tiber;[186] we may take it that the old central fortress of Latium, on the Alban hill, was not in the right position for defence, and that it was seen to be absolutely necessary to make a stronghold of the position offered by the hills which abut on the river twenty miles above its mouth--the only real position of defence for the Latin settlements in its rear. Here an _urbs_ was made with _murus_ and _pomoerium_, _i.e._ material and spiritual boundaries, taking in a space sufficient to hold the threatened rural population with their flocks and herds, with the river in the front and a common citadel on the Capitoline hill, and including the Palatine, Quirinal, Esquiline, Caelian and Aventine hills, though the last named remained technically outside the pomoerium.[187]