But by the early 1990s, Cuba was struggling to take care of them without Soviet aid. The Sudan People's Liberation Army was riven with factions and its leaders seemed more concerned with preserving their power than with the children they had sent abroad. It was also around this time that the tectonic plates of global politics shifted, and it was now the United States and its Western allies that backed the SPLA, while Russia and China lined up with the government in Khartoum.
"We had sometimes to share shoes with classmates," said Daniel Thon Duop, 35, who had fought for the rebels until he left at the age of 13.
After 10 years, they'd finished medical school, but Cuba could no longer support grand projects like the Island of Youth and there was no place for them.
Finally, in 1995, Cuba enlisted the help of the United Nations, which gave the students refugee status and looked for someone else to take them. Some went to Europe, and a few to the United States. Canada took in the doctors.
THE TRUE NORTH
Canada offered more opportunity than Cuba, but not in the field the doctors wanted. While they had completed medical school, they had not finished an internship or a residency, and Canadian institutions would not accept their credentials. They spoke Arabic, Spanish, some Portuguese and the language of their ethnicities - Dinka, Nuer, Anuak - but not English or French.
They also had families back home in south Sudan to support. Many could only find minimum-wage jobs working at meat-packing plants in Brooks, Alta., and in Winnipeg. Dr. Deng sold contracts for Direct Energy. Dr. Tut Pur worked as a physical therapist. Okony Simon Mori, 36, tried to volunteer in a hospital, but couldn't find anyone to take him. He worked with disabled children instead and at a meat-packing plant.
In 2005, after the civil war finally ended, Dr. Thon Duop caught word of Samaritan's Purse, an evangelical Christian group led by Franklin Graham, the son of Billy Graham, that declares on its website "first-class treatment in the Name of the Great Physician."
Samaritan's Purse has worked in south Sudan since 1993. Dr. Thon Duop decided that he would ask the charity to train all those doctors well enough to complete their mission and go home.
"He kept mentioning this word mission, that they were on a mission," recalls John Clayton, projects director for Samaritan's Purse Canada. "They've been living with that sense of destiny and calling in their lives ever since."
Samaritan's Purse approached the medical school at the University of Calgary in 2005. The plan was for a refresher course before the group returned home. It lasted for nine months, but did not go as planned.
The doctors had been out of medical school for as long as seven years and some were still struggling with English. They needed to be trained in basic techniques - scrubbing themselves down before surgery, for example.
For the past year, the doctors have been in Kenya completing the equivalent of the residency program that they never received after medical school in Cuba.
It has been another difficult time. Some of the doctors were struggling with alcohol abuse, and some still do.
"Everybody's hoping and wishing for the best ... but not taking quite as much stock of how really degraded their knowledge and skills were from all those years. Which is nothing against them," said Scott Shannon, an American doctor who is running their training program in Kenya.
One of the original 15, one of two women in the group, decided not to continue. Another went on to south Sudan without finishing the Kenya program because Dr. Shannon ultimately decided he would never be ready to be a doctor. The first three of the remaining 13 are finally returning home this month to fulfill Mr. Garang's commandment. The remaining 10 will return home early next year.