His voice is light, sincere and boyish as he talks about his short but eventful life. His earliest memories are of war songs: "Men chanting, women ululating, songs to celebrate victory, and to console them for the loved ones they lost." The drum-backed music of the villages was a peaceful kind of rap, he says, but in his town the music was for war.
Jal is reluctant to talk about the five years he spent in the bush after his forced induction into a rebel army at the age of eight - "It drains me to tell" - and his story, as it emerges, is indeed almost unbearable. Civil war had raged in Sudan since the Fifties, but when the Muslim government in the north imposed sharia law, the Sudan People's Liberation Army in the south mobilised against it. Jal's father, a policeman, joined the insurgency, while Jal and his mother moved from village to village to evade hostilities. She died when he was seven, and he was evacuated to "safety" in Ethiopia where, when the aid agencies weren't looking, the SPLA gave him an AK47 and sent him into battle.
When the SPLA split into warring factions, Jal and several hundred boys fled across the desert. After fighting, starvation, animal attacks and suicides, only a handful of them made it to a rival camp.
There, his luck turned: a British aid worker, Emma McCune, adopted him and put him on a flight to Nairobi. His trajectory now intersected with history: the story of McCune, who had married a rebel leader and was shortly afterwards killed in a car crash, was seized on by the film-maker Tony Scott, who is now making a biopic in which Nicole Kidman will star.
"All that was a big culture shock," Jal says. "I was disarmed and taken to a school in Kenya. I felt lost without my gun. It took time to learn to live with people without fighting them. I kept getting expelled for getting into fights. And I was haunted by terrible memories, like the time I had no food or water and was tempted to eat a human being."
At 20, music entered his life. "When I went to church, I saw people dancing and singing. They were obviously happy. And I suddenly thought: if the God they were praying to in church was the same God who helped me when I was suffering so much, could I perhaps write for him some songs? So I did. I got a group together, and we performed in churches with piano and drums. We asked people who came to our concerts to bring a packet of flour, as many people in Kenya needed food."
His first recorded song, "Praise the Lord", became a hit, and his second, "Gua", in which he rapped in Arabic, English, Dinka and his native Nuer, topped the charts in Kenya for eight weeks. When it was licensed for the Rough Guide to the Music of Sudan, together with a song by the 58-year-old singer and oud player Abdel Gadir Salim (a Muslim from the north), the idea germinated for their joint album, Ceasefire.
Appearing for Live8 in Cornwall last year, Jal got into a famous row with Sir Bob Geldof over that pointed piece of marginalisation. He has no hard feelings now. "English audiences are very supportive," he says. "They're not as hard as African audiences."
Why so? "In Africa almost everyone can sing. You have to be extraordinarily good to impress them." When Jal tours this month with Amadou and Mariam and Souad Massi, as African Soul Rebels, that should not be a problem.
The African Soul Rebels tour starts at Bridgewater Hall, Manchester, on 17 February and continues to 4 MarchReuse content