There was a real "Amala", a "Great Mother". Her name was Diki Tsering and she was the mother of HH The 14th Dalai Lama.
This is a photograph of her taken by Heinrich Harrer, the author of the book "Seven Years in Tibet". Her daughter, Jetsun Pema, portrayed her in the film.
The Dalai Lama has said that she was a very kind and considerate person and, even with all the troubles she experienced herself, she was always ready to help others. He has also stressed that mothers are extremely important and are sometimes under valued given their vital roll in bringing up the world.