The actress was speaking exclusively before the screening of First They Killed My Father, a true-life account of the Khmer Rouge genocide through the eyes of a child.
She said she hoped the film, which she directed, would help Cambodians to speak more openly about the trauma of the period.
Two million people died.
Jolie, now a UN refugee agency special envoy, first visited Cambodia for the filming of 2001 hit Lara Croft: Tomb Raider.
She later adopted Maddox, her oldest son, from Cambodia.
“I came to this country and I fell in love with its people and learned its history, and in doing so learned, how little I actually knew about the world.”
“This country, for me was my awakening.
“I’ll always be very grateful to this country. I don’t think I ever could give back as much as this country has given me.”
‘Not properly understood’
First They Killed My Father is based on a book of the same name by Loung Ung.
Ms Ung was five when she and her family were forced to leave their home in the capital, Phnom Penh, by the Khmer Rouge, the regime which ran the country between 1975 and 1979, under Pol Pot.
It is estimated that about two million people, around a quarter of the population, were either murdered by the regime or died from starvation and overwork.
“I thought that this war that happened 40 years ago, and what happened to these people, was not properly understood,” said Jolie.
The film is predominantly in the local Khmer language, and Jolie said that while she wanted the wider world to better understand events in Cambodia she hoped it would have an impact domestically too.
“I hope it helps the country speak more,” she said, as many survivors “haven’t told their children their story”.