Uruk (//; Sumerian: Cuneiform: 𒀕𒆠, unugki, Akkadian: 𒌷𒀕 or 𒌷𒀔 Uruk (URUUNUG); Arabic: وركاء or أوروك, Warkāʼ or Auruk; Aramaic/Hebrew: אֶרֶךְ ʼÉreḵ; Ancient Greek: Ὀρχόη, romanized: Orkhóē, Ὀρέχ Orékh, Ὠρύγεια Ōrúgeia) was an ancient city of Sumer (and later of Babylonia) situated east of the present bed of the Euphrates River on the dried-up ancient channel of the Euphrates 30 km (19 mi) east of modern Samawah, Al-Muthannā, Iraq.
Uruk is the type site for the Uruk period. Uruk played a leading role in the early urbanization of Sumer in the mid-4th millennium BC. By the final phase of the Uruk period around 3100 BCE, the city may have had 40,000 residents, with 80,000-90,000 people living in its environs, making it the largest urban area in the world at the time. The legendary king Gilgamesh, according to the chronology presented in the Sumerian king list, ruled Uruk in the 27th century BC. The city lost its prime importance around 2000 BC in the context of the struggle of Babylonia against Elam, but it remained inhabited throughout the Seleucid (312–63 BC) and Parthian (227 BC to 224 AD) periods until it was finally abandoned shortly before or after the Islamic conquest of 633–638.
The Arabic name of Babylonia, which eventually became the name of the present-day country, al-ʿIrāq, is thought to derive from the name Uruk via Aramaic (Erech) and possibly via Middle Persian (Erāq) transmission. In Sumerian, the word uru could mean "city, town, village, district".