India launched strikes against Pakistan on Wednesday, two weeks after a deadly terrorist attack on the Indian-controlled side of the disputed Kashmir region intensified hostilities between the archrival nations. Pakistani officials said more than 20 people had been killed in the strikes, and the country vowed to respond at “a time and place of its own choosing.”

India was retaliating for the April 22 attack in Kashmir, which it has suggested Pakistan was behind. Pakistan has repeatedly denied that claim. More than two dozen civilians were killed in the massacre, most of them Hindu tourists.

The confrontation is only the latest escalation of a decadeslong conflict over Kashmir, a scenic valley in the Himalayas that is wedged between the two nuclear-armed nations. Kashmiris have rarely had a say in their own fate.

Here is a history of the dispute.

1947

Fraught Beginnings

Contention over Kashmir began nearly as soon as India and Pakistan were formed.

In 1947, Britain divided India, its former colony, into two countries. One was Pakistan, with a Muslim majority. The other, made up mostly of Hindus, kept the name India. But Kashmir’s fate was left undecided.

Within months, both India and Pakistan had laid claim to the territory. A military confrontation ensued. The Hindu ruler of Kashmir, who had at first refused to abdicate his sovereignty, agreed to make the region part of India in exchange for a security guarantee, after militias from Pakistan moved into parts of his territory.