Samina Akram was 12 when the trains began arriving in Lahore: some with people spilling out of doors and windows, others full of dead bodies. On the roads outside the city, families were arriving on foot or by truck.

“There were children who had been left by their mothers,” Akram remembers. “Children with masses of flies on their faces. I’ve never seen so many vultures just waiting to swoop.”

In one of those trucks was Ibn Abdur Rehman, then 17, whose family had left Hasanpur, 300 miles away in Uttar Pradesh. Shortly after their town had become part of India, a mob descended on his grandfather’s house and massacred scores of his relatives.

“There was lawlessness. It was systematic plunder,” Rehman remembered. “Everybody was afraid.”

Lahore, capital of Punjab, became part of Pakistan, having been disputed until the last minute partly because of its large Hindu and Sikh populations. The uncertainty caused tensions to flare, with stabbings, violence and riots across the city.

“I was rather apprehensive. One couldn’t feel comfortable,” said Akram.

As the capital of the Mughal empire from 1524 to 1752, Lahore was a multicultural crossroads. Faith was only one of several markers of identification, until it was imposed in 1947 as the one that determined where people should live.

Akram is from a Muslim family but had little notion of religious differences. Her first and best friend from the age of three was Mahesh, a Hindu boy who lived across the street. One day in 1947, nine years after they’d met, she returned from a holiday to find his family gone.

“It was like having an empty space in your heart,” Akram tells the Observer. She still keeps a black-and-white photograph of Mahesh’s family in her bedroom. At 82, she has outlived her army officer husband, but still lives in their beautiful house, built around a garden full of chirping birds.

Today, Lahore is a fast-paced, cosmopolitan city, Pakistan’s cultural capital. “If you haven’t seen Lahore, you haven’t been born yet,” goes a saying. But beneath the bustle of 10 million people runs a current of unspoken trauma. The partition generation is shrinking, and few of them have shared their stories. There have been no official efforts to collect their memories of 1947.

“Partition survivors think their children will never understand what they’ve been through,” says Furrukh Khan a professor at Lahore University who has been interviewing women about partition for 20 years and is now working on a documentary.

And children, for their part, are reluctant to ask parents sensitive questions. “Parents are these towering figures,” he says. “We were never able to relate to them.”

Every year, Pakistan celebrates partition, or Independence Day, with prayers, flag-hoisting, green-and-white coloured clothing, military parades and fireworks across the country. This year, the government had planned to inaugurate a new airport on 14 August, but that has been postponed.

Lahore has no museum of partition. No memorials for those killed. Only in recent years have survivors been asked, in a systematic way, to share their stories.The Citizens’ Archive of Pakistan, a non-profit organisation, has interviewed more than 1,000 survivors and is planning an interactive exhibition at the National History Museum in Lahore. As well as preserving history, these stories capture how overwhelmingly anti-Indian the official state narrative was, says Anam Zakaria, 29, author of a 2015 oral history book, Footprints of Partition.

Schools don’t teach history, she adds, only Pakistan studies. And because her generation is taught a skewed history, they are often oblivious to what their grandparents know: that people on either side of the border share culture. They are not just separated by tragedy but united in it too.

“The younger generations receive a packaged history,” Zakaria says. Documenting partition experiences is urgent: the generation who saw it is nearly gone. “That’s my biggest fear. They’re the only ones who have a more nuanced view of history.”

Women’s memories and traumas, in particular, remain pent up for decades. “One woman spoke to me about partition for a long time, and fainted afterwards,” Zakaria says.

The partition nearly doubled Lahore’s population. The exodus of affluent Hindus and Sikhs removed cultural capital, but new communities contributed to the city’s revival. As part of India, Lahore had been a centre of film and newspaper publishing, rivalled by Mumbai and Kolkata, but as part of Pakistan it became a cinematic capital.

“Habits changed. Food changed,” says Rehman.

With time, the trauma of 1947 became a source of creativity. Short story writer Saadat Hasan Manto, who came to Lahore from Mumbai in 1948, uses partition prominently in his work. His 1955 story Toba Tek Singh, which tells of a group of mental asylum patients evicted from Pakistan, ends with an old man collapsing in the no man’s land between the two countries.

Despite political hostility between India and Pakistan, creeping religious extremism and a degree of lawlessness, Lahore still prides itself on its tolerance. On the border, Muslims, Hindus and Sikhs congregate for festivals – melas – and pray at the same shrines. “If they opened the gates, people would run towards each other,” says Rehman.

Like many, he has managed to visit his old house, in Hasanpur. In 1988, it stood unoccupied, bloodstains still painfully visible on the walls.

Akram was reunited with her childhood friend two decades ago. Mahesh Buch was by then an urban planner, known as the modern architect of the city of Bhopal. He died two years ago but in a memoir recalled meeting Akram in Bhopal. The first thing she asked, he wrote, was: “Does Aunty’s [his mum’s] hair still come down to her ankles?”

Then the friends went sightseeing, visiting every corner of the city where Buch had arrived as a child, but which he had, literally, made his own.

“My God, we didn’t sit still,” Akram laughs. “It was like we had never been apart. He was the Mahesh I’d known.”