In August 1947, British colonialists left India, dividing the country into two states - India and Pakistan.
The new film Viceroy's House explores the events leading up to the partition and its devastating aftermath.
Director, writer and producer Gurinder Chadha said it was a very personal story with global ramifications.
"I always grew up under the shadow of partition," Ms Chadha told SBS.
Based on formerly secret British documents, the film follows the end of an empire as the final Viceroy of India, Lord Mountbatten, prepared to divide the country into Hindu-majority India and Muslim-majority Pakistan.
"People who lived on the wrong side of those borders suffered, including my family who came from the side of Punjab that is now Pakistan," Ms Chadha explained.
Her grandparents were among the millions of people who fled when Pakistan was created.
Her aunt, aged two, was one of many who died of starvation.
"My family immediately became refugees, like 40 million people at that time," she said.
"It's the largest forced migration of humans in history. But very few people know about it."
She believes many of the families impacted by the partition still carry psychological scars from that time.
"Obviously the British Empire doesn't want to talk about it, but also the families involved don't want to talk about it," she said.
She says the "truth" she discovered in researching the film is very different from what she was taught at school.
Hugh Bonneville, Gurinder Chadha and Gillian Anderson at the film's London premiere. Source: AAP
"Although it was a tragic event, for me it was important to make a film where we could look at what happened," she said.
After building a following through films like Bend it Like Beckham and Bride and Prejudice, Ms Chadha hopes her latest offering will generate discussion around current geopolitical events.
"The message really of the film is that is much easier for politicians to divide us, than it is to lead us."
Viceroy's House, starring Gillian Anderson and Hugh Bonnerville, opens nationally on May 18.
