The Hindu Vedas mention a river named Sarasvati. In Sanskrit 'saras' means a lake or water body, and 'vati', means a female associated with it. Sarasvati was the biggest and most important of the seven holy rivers of the Rig Veda.In the Rig Veda the Sarasvati River is mentionned fifty times (e.g. Rig Veda II.41.16; VI.61.8-13; I.3.12.), while there are several references to the Sapthasindhu, the "land of the seven rivers". In the Rig Veda (7:95:2) it is said that the Sarasvati surpasses in majesty and might all other rivers, and Rig Veda 7:36:6 calls it the mother of rivers.
The river has been identified with various present-day or historical rivers, particularly the Ghaggar-Hakra river in India and Pakistan; this course continues into the Raini Nala riverbed. Alternative suggestions include the Helmand River in Afghanistan, which historically bore the name Harahvaiti, which is the Avestan form for "Sarasvati". However, this Afghan river flows into a small lake in the Iranian plateau, which does not match the Rig Vedic description of a "sea going" river. There is also a river in Iran which has been given this name. Sometimes it also means the heavenly 'river' - i.e. the milky way - and it is also personified as a goddess. The goddess Sarasvati was originally a personification of this river, and later developed an identity and meaning independently from the river. There is also a present-day Saraswati River in India which appears to be one of the branches of the ancient river.
Satellite photography has shown that there was indeed a large river in the northwest of India, that dried up between ca. 2500 to 2000 B.C. The river bed was three to ten kilometers wide. The Sarasvati once drained the Sutlej and Yamuna Rivers. The Sutlej and Yamuna Rivers have changed their courses over the time. (see for example Studies from the Post-Graduate Research Institute of Deccan College, Pune, and the Central Arid Zone Research Institute (CAZRI), Jodhpur. Confirmed by use of MSS (multi-spectoral scanner) and Landsat satellite photography. Note MLBD NEWSLETTER (Delhi, India: Motilal Banarsidass), Nov. 1989.)
Paleobotanical information documents the aridity that developped after the drying up of the river. (Gadgil and Thapar 1990 and references therein). The disappearance of the river may have been caused by earthquakes. It may have been one of the causes for the decline of the Indus Valley Civilization. The largest concentration of Indus Valley sites appears to be east of the Indus, at and near the region where once the ancient Sarasvati River flowed.
The identification of the 'original' Saraswati river has become embroiled in debates about the age of the Vedas and of the relation between Aryan culture and the Indus Valley civilization (IVC). In the enumeration of the rivers in Rigveda 10.75.05, the order is Ganga, Yamuna, Sarasvati, Shutudri (= Sutlej). Hence it is quite clear that one of the rivers given the name 'Sarasvati' flowed through Haryana and Rajasthan. The question is whether this is the primal 'Sarasvati'. The Rigveda says that this Sarasvati rises in the mountains and ends up in the sea (e.g. RV VII.95.2); it describes a man sailing up the Sarasvati from the sea to the mountains. The Brahmanas, which are later texts than the Rig Veda, mention that the Sarasvati flowed through a desert; the Mahabharata, which was written still later, says that the Sarasvati dried up in a desert, possibly the Thar Desert. Recent finding suggest the Ghaggar-Hakra river did once flow in great strength, and was of major importance to the Indus Valley Civilization, but that it dried up due to the redirection of its tributaries, and loss of rainfall in much of its catchment area due to deforestation and overgrazing in what is now Pakistan, at the latest in 1900 BC, but perhaps much earlier. Clearly this is of great importance in establishing the date of the Rigveda. If the Ghaggar-Hakra river is the original Sarasvati of the Vedas, it implies that the Vedic Aryans were resident in the Indus at the height of the IVC. If it was the Afghan Helmand river, it may support the so-called Aryan invasion theory, as well as other scenarios.
Along the course of the Ghaggar-Hakra river are many archaeological sites of the Indus Valley Civilization; but not further south than the middle of Bahawalpur district. It could be that the permanent Sarasvati ended there, and its water only reached the sea in very wet rainy seasons. It may also have been affected by much of its water being taken for irrigation.
In the Manu Samhita (II.17-18), the sage Manu, escaping from a flood, founded the Vedic culture between the Sarasvati and Drishadvati rivers. In the Shatapatha Brahmana there is a description of the God Agni burning out rivers, which may be a reference to the drying up of rivers. Indra was the river deity of the Sarasvati river, the disappearance of the Sarasvati river may have been one of the causes for the diminishing popularity of Indra in Vedic culture. Indra may have been "replaced" by the similar deity Shiva, who is the river deity of the Ganges.