Tigris
The Tigris (Hebrew Hiddekel; Greek Tigris) is one of the two great rivers of Mesopotamia, rising in the mountains of eastern Turkey and flowing approximately 1,150 miles southeast to join the Euphrates before emptying into the Persian Gulf. In the Table of Nations it is listed as one of the four rivers flowing from Eden: "the third river is the Tigris, which flows east of Assyria" (Gen. 2:14).
The Tigris formed the eastern boundary of the Assyrian heartland, and major Assyrian cities — Nineveh, Ashur, Calah — lay along its banks. Daniel received his vision of the man clothed in linen while standing on the bank of the great river, which some identify as the Tigris (Dan. 10:4). The Greek and Syriac traditions uniformly identify the Hebrew Hiddekel with the Tigris. The river was a commercial artery and military corridor for successive empires from Mesopotamia through the Persian period and remains a major river of modern Iraq.