From the narrow Gravias - Ambliani pass, the Pelasgian - Dryopian pass, named after the strong Pelasgian walls, known as the ancient Mycenaean - Dorian Passage, due to the Mycenaean (Dorian) road of the Dorian Tetrapolis or by its more recent name, "Historic Narrow Passes of Gravias - Ambliani" or "51st kilometer" from the National Resistance, as an intermediate road section of the great Mycenaean and Dorian Corridor, which connected communicatively the upper course of Kifisos (upper Kifisos valley) with the Malian Gulf (north) and southward with the Corinthian Gulf.
All the ancient Greek tribes and almost all the invasions of the Northern tribes of Europe and the known Asian tribes passed through this (geo)strategic passage, which through the narrows of the ancient unified Oiti with Kallidromo ended up in the upper Kifisos valley, at the northern entrance of the Historic Narrows, with some invaders continuing south to Delphi, ancient Amphissa up to the Corinthian Gulf, or following an eastern path of destruction, parallel to that of the river Kifisos, towards Boeotia, Attica, up to the Isthmus of Corinth (Peloponnese).
Some of these invaders stayed, leaving their social imprint (micro-toponyms, loanwords of agricultural-pastoral vocabulary, etc.) in the upper valley and its mountainous regions.
The inhabitants of the remaining Dorian settlements, Voio and Erineos of the upper valley after 535 AD were also forced to leave due to frequent invasions to the mountains of the surrounding peaks (Parnassus, Giona, Oiti, Kallidromo) and others to neighboring or more distant areas of the Greek Peninsula.
The new settlements created after their departure around the Historic Narrows of Gravias-Ambliani, Varbena, Variani, Soniska, Chlomos, Kastelli, Panassari, Paliambela, Diplopites (Diplopita), Ambliani (some recorded for the first time historically in the present work, perhaps others remain unknown yet...), however, withstood through time and the brutal occupation of the successive invading conquerors.
