The Himalayan border between India and China has been disputed for centuries, but the two countries have been fighting over it most recently since the 1960s.
In the 18th century it was fought over by the Russian, Chinese and British empires, and after India gained independence ownership of the region became more confused.
China values the region because it provides a trading route to Pakistan, and recent hostilities have been sparked by fears in Beijing that India will cut it off from the crucial overland corridor.
The current official border between the two was set by Britain and is known as the McMahon line. It is recognised by India but not by China.
In reality, the border between the two countries is on Line of Actual Control (LAC) where Indian and Chinese forces finished after the Sino-Indian War of 1962.
At least 20 Indian soldiers, including a colonel, were killed and at least 43 Chinese men were wounded or killed last Monday night along the Line of Actual Control (LAC), a disputed border in the Himlayas (the red territory is controlled by India, and the beige and grey stripes, Aksai Chin, is Chinese but claimed by India, the white line which surrounds is what Indian believes its border should be, whereas the black line was agreed after then 1962 Sino-Indian War – a heavy defeat for India)
Aksai Chin, the site of the latest tensions, is located in India according to the official border but is claimed as part of the Chinese region of Xinjiang by Beijing.
It is an almost uninhabited high-altitude scrubland traversed by the Xinjiang-Tibet Highway.
The other disputed territory is hundreds of miles away to the east of Tibet.
The 1962 Sino-Indian War was fought on these two frontiers as Indian Prime Minister Jawaharlal Nehru put it, a struggle over land where ‘not even a blade of grass grows.’
In addition to the disputed border, China had seized Tibet ten years before and accused India of trying to to subvert Beijing’s interests by granting asylum to the Dalai Lama.
There was also a Cold War element and India wanted to see if the US would back it in a confrontation against communist China.
Delhi had ignored the desolate corner of the subcontinent which allowed the Chinese to build a military road through it during the 1950s to connect the province of Xinjiang to Tibet.
The Indian discovery of this highway was a major factor which led to ferocious clashes leading up to the war.
Yet the Indians had just two divisions posted at the border when the Chinese invaded, never suspecting that Beijing would be so bold as to cross the McMahon Line.
The war lasted for one month and left more than 2,000 dead on both sides. It was a heavy defeat for India and led to the new border, the LAC, being established and pushing India back from McMahon line.
Uninhabitable desert: The Galwan Valley where the mass brawl between the Indian and Chinese forces took place. The Chinese interest in the region surrounds President Xi Jinping’s centrepiece ‘Belt and Road’ policy to have vast infrastructure throughout the old Silk Road. Beijing fears that increased Indian presence in the region will cut off its trade route to Pakistan
Much of the reason for the ongoing conflict is the ill-defined border, the result of a confused status the region had during the colonial era, which was made more murky by India’s war with Pakistan in 1947.
Chinese interest in the region surrounds President Xi Jinping’s centrepiece ‘Belt and Road’ foreign policy to have vast infrastructure throughout the old Silk Road.
Beijing fears that increased Indian presence in the region will cut off its trade route to Pakistan.
The two sides have blamed each other for recent hostilities but analysts say India’s building of new roads in the region may have been the fuse for May’s standoff.
Both sides have dispatched reinforcements and heavy equipment to the zone.