[many U'laf] (Heb. Ulay', אוּלִי [in pause אוּלָי], probably Pehlvi Am- Halesh, i.e. "pure water;" Sept. Οὐλαϊv; Theodotion, Οὐβάλ; Vulg. Ulai) is mentioned by Daniel (Da 8:2,16) as a river near Susa, vhere he saw his vision of the ram and the he-goat. It has generally been identified with the Eulceus of the Greek and Roman geographers (Marc. Heracl. p. 18; Arrian, Exp. A 1. 7:7; Strabo, 15:3,22; Ptolemy, 6:3; Pliny, t. N. 6:31), a large stream in the immediate neighborhood of that city. This identification may be safely allowed, resting as it does on the double ground of close verbal resemblance in the two names, and complete agreement as to the situation. The Eulaeus has been by many identified with the Choaspes, which is undoubtedly the modern Kerkhah, an affluent of the Tigris, flowing into it a little below Kurnah. By others it has been regarded as the Kuran, a large river considerably farther to the eastward, which enters the Khor Bamishir, near Mohammerah. Some have even suggested that it may have been the Shapur or Sha'ur, a small stream which rises a few miles N.W. of Susa, and flows by the ruins into the Dizful stream, an affluent of the Kuran.
1. The general grounds on which the Eulaeus has been identified with the Choaspes, and so with the Kerkhah (Salmasius, Rosenmüller, Wahl, Kitto, etc.), are the mention of each separately by ancient writers as "the river of Susa," and, more especially, the statements made by some (Strabo, Pliny) that the water of the Eulaeus, by others (Herod, Athenaeus, Plutarch, Q. Curtius) that that of the Choaspes, was the only water tasted by the Persian kings. Against the identification it must be noticed that Strabo, Pliny, Solinus, and Polyclitus (ap. Strabo, 15:3, 4) regard the rivers as distinct, and that the lower course of the Eulaeus. as described by Arrian (Exp. A 1. 7:7) and Pliny (I. N. 6:26), is such as cannot possibly be reconciled with that of the Kerkhah river.
2. The grounds for regarding the Eulaeus as the Kuran are decidedly stronger than those for identifying it with the Kerkhah or Choaspes. No one can compare the voyage of Nearchus, in Arrian's Indica, with Arrian's own account of Alexander's descent of the Eulaeus (7, 7) without seeing that the Eulaeus of the one narrative is the Pasitigris of the other, and that the Pasitigris is the Kuran is almost universally admitted. Indeed, it may be said that all accounts of the lower Eulaeus those of Arrian, Pliny, Polyclitus, and Ptolemyidentify it, beyond the possibility of mistake, with the lower Kuran, and that so far there ought to be no controversy. The difficulty is with respect to the upper Eulaeus. The Eulueus, according to Pliny, surrounded the citadel of Susa (6, 27), whereas even the Dizful branch of the Kuran does not come within six miles of the ruins. It lay to the west, not only of the Pasitigris (Kuran), but also of the Coprates (river of Dizful), according to Diodorus (19, 18, 19). So far, it might be the Shapur, but for two objections. The Shapur is too small a stream to have attracted the general notice of geographers, and its water is of so bad a character that it could never have been chosen for the royal table (Geogracph. Journ. 9:70). There is also an important notice in Pliny entirely incompatible with the notion that the short stream of the Shapur, which rises in the plain about five miles to the N.N.W. of Susa, can be the true Eulaeus. Pliny says (6, 31) the Eulaeus rose in Media, and flowed through Mesobatene. Now, this is exactly true of the, upper. Kerkhah, which rises near Hamadan (Ecbatana), and flows down the district of Mahsabadan (Mesobatene).
The result is that the various notices of ancient writers appear to identify the upper Eilaeus with the upper Kerkhah, and the lower Eulaeus, quite unmistakably, with the lower Kuran. A recent survey of the ground has suggested a satisfactory explanation. It appears that the Kerkhah once bifurcated at Pai Pul, about twenty miles north-west of Susa, sending out a branch which passed east of the ruins, absorbing into it the Shapur, and flowing on across the plain in a S.S.E. direction till it fell into the Kuran at Ahwaz (Loftus, Chaldea and Susiana, p. 424, 425). Thus, the upper Kerkhah and the lower Kuran were in old times united, and might be viewed as forming a single stream. The name Eulaelus (Ulai) seems to have applied most properly to the eastern branch stream from Pai Pul to Ahwaz; the stream above Pai Pul was sometimes called the Eulseus, but was more properly the Choaspes, which was also the sole name of the western branch, or present course, of the Kerkhah from Pai Pul to the Tigris. The name Pasitigris was proper to the upper Kuran from its source to its junction with the Eulaeus, after which the two names were equally applied to the lower river. The Dizful stream, which was not very generally known, was called the Coprates. It is believed that this view of the river names will reconcile and make intelligible all the notices of them contained in the ancient writers. It follows from this that the water which the Persian kings drank, both at the court and when, they traveled abroad, was that of the Kerkhah, taken probably from the eastern branch, or proper Eulaeus, which washed the walls of Susa, and (according to Pliny) was used to strengthen its defenses. This water was, and still is, believed to possess peculiar lightness (Strabo, 15:3, 22; Geograph. Journ. 9:70), and is thought to be at once more wholesome and more pleasant to the taste than almost any other.
See Porter, Travels, 2, 412; Kinneir, Persian Empire, p. 100-106; Sir H. Rawlinson, in Geograph. Journ. 9:84-93; Layard, ibid. 16:91-94; Loftus, Chaldea and Susiana, p. 424-431.