The bloodshed sparked by their division at independence in 1947, and numerous wars since, have entrenched hostility that continues to animate politics on both sides of their shared frontier.

AFP reviews the key moments in the fraught and often violent relationship between the two neighbours:

- 1947: Partition and war -

Lord Mountbatten, the last viceroy of India, brings the curtain down on two centuries of British rule at the stroke of midnight on August 15, 1947.

The Indian sub-continent is divided into mainly Hindu India and Muslim-majority Pakistan.

The poorly prepared partition unleashes sectarian bloodshed that kills possibly more than a million people and displaces 15 million others.

The monarch of Muslim-majority Kashmir, sandwiched between both countries and below the Himalayan mountain range, dithers on whether to submit to Indian or Pakistani rule.

Militants backed by Pakistan attack the territory after the suppression of local uprisings against the monarch's rule, prompting him to seek India's help repelling them and precipitating an all-out war between both countries.

A UN-backed, 770-kilometre (478-mile) ceasefire line in January 1949 becomes a de facto frontier dividing Kashmir, now known as the Line of Control and still heavily militarised on both sides.

- 1965-71: Kashmir and Bangladesh wars -

Pakistan launches a second war in August 1965 when it invades Kashmir, seeking to bring the divided territory entirely under its control.

The conflict ends inconclusively seven weeks later after a ceasefire brokered by the Soviet Union with thousands of soldiers dead on each side.

Pakistan deploys troops at the start of 1971 to violently suppress a growing independence movement in what is now Bangladesh, which it had governed since 1947.

An estimated three million people are killed in the nine-month conflict and millions more cross into India with harrowing stories of atrocities by Pakistani troops.

India mobilises a full invasion of Bangladesh at the end of the year, forcing Pakistan's surrender less than two weeks later.

Prime Minister Indira Gandhi's popularity reaches stratospheric heights as a result of the quick victory, bolstered further when her government announces India's first successful nuclear weapons test three years later.

- 1989-90: Rebellion in Kashmir -

An uprising breaks out in Kashmir in 1989 as longstanding grievances with Indian rule boil over, worsened by a territorial election that locals accuse authorities of rigging.

Hindus and other minorities flee the region over the following year after targeted assassinations, assaults, and threats by rebel fighters.

Tens of thousands of soldiers, rebels and civilians are killed in the following decades during periodic battles between security forces and militants.

Widespread human rights abuses are documented on both sides of the conflict.

India accuses Pakistan of funding the rebels and aiding their weapons training on its territory.

- 1998-99: Nuclear weapons and Kargil conflict -

Pakistan conducts its first public nuclear weapons tests in 1998 in response to another round of tests by India weeks earlier.

The UN Security Council unanimously condemns both governments and orders them to refrain from more tests, while the United States imposes economic sanctions on both countries.

Pakistan-backed militants cross into Indian-administered Kashmir the following year, seizing military posts in the icy heights of the Kargil mountains.

Raja Mohammad Zafarul Haq, a leading member of Pakistan's ruling party, says his country will not refrain from using nuclear weapons to protect its security if necessary.

Pakistan yields after severe pressure from Washington, alarmed by intelligence reports showing Islamabad had deployed part of its nuclear arsenal nearer to the conflict.

Prime Minister Nawaz Sharif blames army chief Pervez Musharaf for igniting the conflict, which killed at least 1,000 people over 10 weeks, without his knowledge or approval.

Musharaf overthrows Sharif in a coup months later.

- 2008-Present: Mumbai attacks and Modi -

Islamist gunmen attack the Indian financial hub of Mumbai in 2008, killing 166 people including 29 foreign nationals.

India blames Pakistan's intelligence service for the assault and suspends peace talks.

Contacts resume in 2011, but the situation is marred by sporadic fighting.

Indian Prime Minister Narendra Modi makes a surprise visit to Pakistan in 2015 but the diplomatic thaw is short-lived.

A 2019 suicide attack kills 41 Indian paramilitary troops in Kashmir and prompts Modi to order tit-for-tat airstrikes inside Pakistan.

The resulting stand-off between the two nations is swiftly defused and Modi is re-elected months later, partly on a wave of nationalist fervour spurred by the military response.