The Maoist movement in India began in 1967, when the villagers of Naxalbari in West Bengal rebelled against local landowners.
Since then, the guerrilla dispute over land rights has grown to 20,000 strong, reaching from northern to southern India.
The Naxalites, as they're also called, have gained control of large areas of land, known as the red corridor, which contains some of India's most underdeveloped land and poorest people.
They believe the government wants to evict villagers in order to free the land for mining companies. They say they have been neglected by the authorities for decades, and instead want to establish a communist society.
The Maoists live a nomadic existence deep in the jungle away from the modern world and have had violent clashes, especially with police... over 6,000 people have died in the dispute.
In April 2010, a rebel ambush killed 76 policemen in the bloodiest single attack so far on the security forces... 285 policemen were killed in total last year.
Civilians have also become involved after the Indian government launched Operation Green Hunt in 2005, arming civilians to fight the Maoists.
But it seems to have increased the violent divide between the two sides... 713 civilians and 171 guerrillas died last year alone.
Premier Manmohan Singh has called the insurgency India's main internal security threat and has urged state governments to increase pro-poor welfare measures to help counter the rebels.
There's also been talk of deploying the army, but such a move would be highly controversial, and the chances of talks with the Maoists to resolve the dispute are also said to be 'slim'.
Sources: BBC, AFP