The Kurukshetra War (Devangari: कुरुक्षेत्र युद्ध) is the war between the Kauravas and Pandavas, which forms an essential component of the Hindu epic Mahābhārata. According to Mahābhārata, a dynastic struggle between sibling clans of Kauravas and the Pandavas for the throne of Hastinapura resulted in a battle in which a number of ancient kingdoms participated as allies of the rival clans. The location of the battle was Kurukshetra in the modern state of Haryana in India.

Mahābhārata states that the war lasted eighteen days during which vast armies from all over the Indian Subcontinent fought alongside the two rivals. Despite only referring to these eighteen days, the war narrative forms more than a quarter of the book, suggesting its relative importance within the epic, which overall spans decades of the warring families.

The narrative describes individual battles of various heroes of both sides, battle-field deaths of some of the prominent heroes, military formations employed on each day by both armies, war diplomacies, meetings and discussions among the heroes and commanders before commencement of war on each day and the weapons used. The chapters (parvas) dealing with the war (from chapter six to ten) are considered amongst the oldest in the entire Mahābhārata. Bhagavad Gita, a sacred text of Vedic philosophy, which recounts the conversation between the Pandava Arjuna and Krishna arising out of Arjuna’s reluctance to fight members of his own family, is considered a later addition to Mahābhārata .

The Kurukshetra War is believed to date variously from 5561 BC to 800 BC, based on the astronomical and literary information from Mahābhārata. The history of the Kurukshetra War is also traced to the Battle of the Ten Kings mentioned in Rigveda.[2]

http://en.wikipedia.org/wiki/Kurukshetra_war