After passing Pylæ, the territory called Babylonia began. The hills flanking the Euphrates, over which the army had hitherto been passing, soon ceased, and low alluvial plains commenced.[72] Traces were now discovered, the first throughout their long march, of a hostile force moving in their front, ravaging the country and burning the herbage. It was here that Cyrus detected the treason of a Persian nobleman named Orontes, whom he examined in his tent, in the presence of various Persians possessing his intimate confidence, as well as of Klearchus with a guard of three thousand hoplites. Orontes was examined, found guilty, and privately put to death.[73] [72] The commentators agree in thinking that we are to understand by Pylæ a sort of gate or pass, marking the spot where the desert country north of Babylonia—with its undulations of land, and its steep banks along the river—was exchanged for the flat and fertile alluvium constituting Babylonia proper. Perhaps there was a town near the pass, and named after it. Now it appears from Col. Chesney’s survey that this alteration in the nature of the country takes place a few miles below Hit. He observes—(Euphrates and Tigris, vol. i, p. 54)—“Three miles below Hit, the remains of aqueducts disappear, and the windings become shorter and more frequent, as the river flows through a tract of country almost level.” Thereabouts it is that I am inclined to place Pylæ. Colonel Chesney places it lower down, twenty-five miles from Hit. Professor Koch (Zug der Zehn Tausend, p. 44), lower down still. Mr. Ainsworth places it as much as seventy geographical miles lower than Hit (Travels in the Track of the Ten Thousand, p. 81); compare Ritter, Erdkunde, West Asien, x. p. 16; xi, pp. 755-763. [73] The description given of this scene (known to the Greeks through the communications of Klearchus) by Xenophon, is extremely interesting (Anab. i, 6). I omit it from regard to space.