following Protoneolithic, or Natufian, occupation is contemporary with the oldest occupation of the nearby open-air site Zawi Chemi Shanidar. M'lefaat on the Khazir River (a tributary to the Great Zab) was a small village of hunter-gatherers dating to the 10th millennium BCE that was contemporary with the Pre-Pottery Neolithic A in the Levant. An archaeological survey of the Citadel of Erbil, in the plain south of the lower course of the Great Zab, has shown that this site was continuously occupied at least from the 6th millennium BCE upward. The earliest historical reference to the region dates to the Ur III dynasty, when king Shulgi mentioned the city of Urbilum – the ancient name of modern-day Erbil. The great Assyrian capitals of Assur, Nineveh, Nimrud and Dur-Sharrukin were all located in the foothill zone where the Great Zab flows into the Tigris, and the Great Zab basin became increasingly integrated into the Middle Assyrian and Neo-Assyrian empires. Nimrud, the capital of the empire until 706 BCE, was located only away from the confluence of the Great Zab with the Tigris. The Assyrian king Ashurnasirpal II constructed a canal called Patti-Hegalli that tapped water from the Great Zab to irrigate the land around Nimrud, and this canal was restored by his successors Tiglath-Pileser III and Esarhaddon. This canal ran along the right bank of the Great Zab and cut through a rock bluff by means of a tunnel and is still visible today. After the fall of the Neo-Assyrian empire, the Medes gained control of the area, followed by the Achaemenids in 550 BCE. The Battle of Gaugamela in 331 BCE – one of the decisive battles leading to the fall of the Achaemenid empire at the hands of Alexander the Great – supposedly took place north of the Great Zab in the vicinity of Mosul. After Alexander’s death in 323 BCE, control of the area shifted to the Seleucids. In 750 CE, the last Umayyad caliph Marwan II was defeated by the Abbasid As-Saffah in the Battle of the Zab on the banks of the Khazir River, a tributary to the Great Zab. When the Mongols swept over Iraq in the 13th century and sacked Erbil, many survivors sought a refuge in the inaccessible valleys of the Great Zab. The Sapna Valley was home to both Christian and Muslim communities, as evidenced by Christian artefacts found at Zawi Chemi Shanidar.