In his Anabasis recounting his march on Babylon with the Persian prince Cyrus in 401 B.C., Xenophon provides his readers with many descriptive details about the area that would come to be called Mesopotamia. He speaks of villages, of wheat, barley and dates, of fields under cultivation and of many other indications of settled life. He also offers a brief description of the flora and fauna of Mesopotamia, in which he mentions wormwood, aromatic shrubs, wild asses, bustards, gazelles and ostriches. Musil, who travelled extensively in this region at the beginning of the twentieth century, commented favourably on the accuracy of some aspects of the picture drawn by Xenophon.
Yet, for all the verisimilitude of Xenophon's description, anyone who has travelled in Mesopotamia, or who is familiar with the accounts of it found in later classical authors such as Strabo or Pliny, cannot help but feel that something is missing in Xenophon's account. What is missing is any reference to pastoral life in the region, particularly the camel pastoralism long associated with Arabia and Arabs. Sheep are mentioned, in passing, only once in the sections of the book devoted to Xenophon's passage through this area, in association with the villages of Cyrus's mother, Parysatis, situated along the upper Tigris, and there is no mention whatsoever of goats or camels, or of nomadic pastoralists who might have herded flocks of such animals. This dearth of positive evidence for nomadism in Xenophon's account might tempt one to conclude that pastoral nomads—at least Arab nomads of the kind described by Strabo and Pliny—had not yet arrived in this area in 401 B.C. But Xenophon himself thwarts such a ready conclusion by calling the part of Mesopotamia lying east of the Khābūr river “Arabia”, a name which in itself implies the existence of Arab nomads.