The only tree which is known to have been anciently cultivated in Mesopotamia is the date-palm; and as this ceases to bear fruit about lat.

35 deg., its greater cultivation could have prevailed only in a very small portion of the country, and so would have affected the general climate but little.

Historically, too, we find, among the earliest notices which have any climatic bearing, indications that the temperature and the consequent condition of the country were anciently very nearly what they now are.

Xenophon speaks of the barrenness of the tract between the Khabour and Babylonia, and the entire absence of forage, in as strong terms as could be used at the present day.

Arrian, following his excellent authorities, notes that Alexander, after crossing the Euphrates, kept close to the hills, "because the heat there was not so scorching as it was lower down," and because he could then procure green food for his horses.