Sindh in 325 BCE under the command of Alexander the Great referred to the Indus River as Indós, hence the modern Indus. The ancient Iranians referred to everything east of the river Indus as hind. The word Sindh is a Persian derivative of the Sanskrit term Sindhu, meaning "river" - a reference to Indus River. Southworth suggests that the name Sindhu is in turn derived from Cintu, a Dravidian word for date palm, a tree commonly found in Sindh. The previous spelling "Sind" (from the Perso-Arabic ) was discontinued in 1988 by an amendment passed in Sindh Assembly, and is now spelt "Sindh." History Ancient era Sindh and surrounding areas contain the ruins of the Indus Valley Civilization. There are remnants of thousand-year-old cities and structures, with a notable example in Sindh being that of Mohenjo Daro. Built around 2500 BCE, it was one of the largest settlements of the ancient Indus civilisation, with features such as standardized bricks, street grids, and covered sewerage systems. It was one of the world's earliest major cities, contemporaneous with the civilizations of ancient Egypt, Mesopotamia, Minoan Crete, and Caral-Supe. Mohenjo-daro was abandoned in the 19th century BCE as the Indus Valley Civilization declined, and the site was not rediscovered until the 1920s. Significant excavation has since been conducted at the site of the city, which was designated a UNESCO World Heritage Site in 1980. The site is currently threatened by erosion and improper restoration. A gradual drying of the region during the 3rd millennium BCE may have been the initial stimulus for its urbanisation. Eventually it also reduced the water supply enough to cause the civilisation's demise and to disperse its population to the east. During the Bronze Age, the territory of Sindh was known as Sindhu-Sauvīra, covering the lower Indus Valley, with its southern border being the Indian Ocean and its northern border being the Pañjāb around Multān. The capital of Sindhu-Sauvīra was named Roruka and Vītabhaya or Vītībhaya, and corresponds to the mediaeval Arohṛ and the modern-day Rohṛī. The Achaemenids conquered the region and established the satrapy of Hindush. The territory may have corresponded to the area covering the lower and central Indus basin (present day Sindh and the southern Punjab regions of Pakistan). Alternatively, some authors consider that Hindush may have been located in the Punjab area. These areas remained under Persian control until the invasion by Alexander. Alexander conquered