Archaeological evidence.  
There is archaeological evidence of human occupation of the area of modern Rome from at least 5,000 years ago, but the dense layer of much younger debris obscures any Palaeolithic and Neolithic sites. Traces of occupation have been found in the general region – including Lavinium and the coast near Ardea – going back to the 15th century BC. The area was home to the Apennine and Proto-Villanovan cultures before the advent of the more regional Latial culture.
Bronze Age.  
Archaeological evidence suggests that Rome developed over a long period, but it was definitely occupied by the middle of the Bronze Age. Core samples have shown that the terrain of Bronze-Age Rome differed greatly from what is present now. The area of the Forum Boarium north of the Aventine Hill was a seasonally dry plain that simultaneously provided a safe inland port for the era's seafaring ships, a wide area for watering horses and cattle, and a safe ford of the Tiber with shallow and slow-flowing water even if Tiber Island had not yet formed, one of the river's major fords between Etruria and Campania. This advantageous but exposed location was closely flanked by the Capitoline, which at that time rose sharply from the more easterly bank of the Tiber and provided a ready citadel for defense and for control of the salt production along the river and at its mouth. The other hills and the marshes between them provided similarly defensible points for settlement.  
Accordingly, thick deposits of manure and ancient pottery shards have been discovered in the Forum Boarium from the middle of the Bronze Age. Current evidence suggests that there were three separate bronze-using settlements on the Capitoline during the period 1700–1350 BC and in the neighboring valley that later became the Roman Forum from 1350–1120 BC. Some 13th century BC structures indicate that the Capitoline was already being terraced to manage its slope. Evidence in the Final Bronze Age around 1200–975 BC is clearer, showing occupation of the Capitoline, Forum, and adjacent Palatine. Excavations near the modern Capitoline Museums suggest the construction of fortifications and some scholars have speculated that settlements also existed on the other hills, especially the Janiculum, Quirinal, and Aventine. The Capitoline currently seems to have been the earliest settled but it is debated whether the settlements on the other hills were independent, colonies of the Capitoline settlement, or formerly separate villages already consolidated into a single polity. By 1000 BC, a necropolis existed in the Forum for cremation graves. By the early Iron Age c. 900 BC, graves started to be placed into the ground. Other cemeteries appear on the Esquiline, Quirinal, and Viminal Hills by the 9th century, containing pottery, imported Greek wares, fibulae, and bronze objects.  Remains from huts on the Palatine have been found that date to the 9th or 8th centuries BC, with accelerating development by the early to middle 8th century BC.  
Eighth and seventh centuries BC.  
By this time, four major settlements emerged in Rome. The nuclei appeared on the Palatine, the Capitoline, the Quirinal and Viminal, and the Caelian, Oppian, and Velia. There is, however, no evidence linking any settlement on the Quirinal hill with the Sabines, as is alleged by some ancient accounts.
The area of the Forum also was converted at this time into a public space. Burials there discontinued and portions of it were paved over. Votive offerings appear in the comitium in the eighth century, indicating a more central religious cult, and other public buildings appear to have been erected around that time. One of those buildings was the domus publica (the official residence of the pontifex maximus), which is now believed to have been constructed between 750 and 700 BC. Religious activity started also in this period on the Capitoline hill, suggesting a connection to the ancient cult of Jupiter Feretrius. Other offerings discovered indicate Rome's connections outside Latium, with imported Greek pottery from Euboea and Corinth.  
The first evidence of a wall appears in the middle or late eighth century on the Palatine, dated between 730 and 720 BC. It is possible that the circuit of the wall marked out what later Romans believed to be the original pomerium (sacred boundary) of the city. The discovery of gates and streets connected to the wall, with the remains of various huts, suggest that Rome had by this time: 
acquired a defined boundary ... and a more sophisticated level of social and political organisation ... the use of the Forum as a public space point[s] to the development of shared civil and ritual space for the inhabitants of all communities, demonstrating an increasing level of centralisation.  
Like other Villanovan proto-urban centres, this archaic Rome was likely organised around clans that guarded their own areas, but by the later eighth century had confederated. The development of city-states was likely a Greek innovation that spread through the Mediterranean from 850 to 750 BC. The earliest votive deposits are found in the early seventh century on the Capitoline and Quirinal hills, suggesting that by that time a city had formed with monumental architecture and public religious sanctuaries. Certainly, by 600 BC, a process of synoikismos was complete and a unified Rome – reflected in the production of a central forum area, public monumental architecture, and civic structures – had by then been formed. 

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