After this, it is almost needless to note that the physical anthropology of the Greeks was quite unimpeded by those literary misconceptions which so long retarded the study of Man in the modern world. Hecataeus, indeed, had at one time been misled by the shortness of Greek pedigrees; but his Egyptian researches gave him in good time the larger perspective,[73] as even his critic Herodotus admits. And the first reporter of the fact that Egypt is the ‘gift of the Nile’ can hardly have failed to see the bearing of this piece of geology upon the question of the antiquity of Man. Herodotus, at all events, has no illusions.[74] Achelous and other rivers are there to show that the Nile is no freak of nature; time future can be postulated to the extent of twenty thousand years; and time past may be measured on the same scale, for the perfecting of the Nile’s gift, not to mention the further periods required for the deposit of the shells in the Pyramid limestone.[75] More explicitly still, he is prepared to allow indefinite time for the development and dissemination of human varieties. _How_ the Danubian Sigynnae came to be colonists of the Medes, he is not prepared to say; but the thing itself is not in his view impossible. γένοιτο δ’ ἂν πᾶν ἐν τῷ μακρῷ χρόνῳ.[76] It is at this point in our story that we must look at the evidence of Aeschylus. Small as is that portion of his works which has come down to us, it is of high value, both as a record of current knowledge, and as an indication of the contemporary phases of theory. Already we have the elements of the later threefold division of the anthropological horizon corresponding essentially with the tri-continental scheme of the geographers, with which we know from a fragment of _Prometheus Solutus_ that Aeschylus was acquainted at a stage of its development, which the quotation fixes for us precisely.[77] Ethnologically, the ἐσχατιαί are as follows:--Northwards, are found the Hyperboreans.[78] Eastwards, lie the Indians; they are camel-riding nomads, and live next to the Aethiopians.[79] Southward come the Aethiopians proper,[80] with Egypt, the gift of the Nile,[81] and Libya. The black skin of the Aethiopians is sun-tanned.[82] Aethiopia embraces everything from the φοινικόπεδον ἐρυθρᾶς ἲερὸν χεῦμα θαλάσσης to the χαλκοκέραυνον παρ’ Ὠκεανῷ λίμναν παντοτρόφον Αἰθιόπων where the Sun rests his horses;[83] that is, from the southern margin of Asia (where the Indians live) to the far South-West. In front of the Aethiopians lie the Libyans; in front of the Indians the Empire of Persia (for there are no Indians in the _Persae_, and Bactria is the remotest province); in front of the Hyperboreans, the Scythians, the Abioi of Homer, and the Arimaspi; all nomad pastoral peoples.