A Dakar court on Monday sentenced a Franco-Senegalese man to 15 years of hard labour for "terrorism" and began the trial of 30 other people facing similar charges.
Prosecutors had sought a life term for Ibrahima Ly, 34, who went to join the Islamic State in Syria.
Ly's phone had photos of him holding a gun and a video in which he exhorts Muslims to wage jihad.
Ly, who is from the western Paris suburb of Trappes, said he had gone to Syria to study the Koran and not to fight. He had been in detention in Senegal for three years.
The court also began the trial of 30 people, including an imam, who are accused of trying to create an "IS base" in southern Senegal before extending it to nearby countries such as The Gambia, Guinea and Guinea-Bissau.
The imam Alioune Ndao and three female co-accused are suspected of planning suicide attacks targeting French nationals and public buildings.
IS propaganda material, weapons and money were found at the homes of the accused, who all deny the allegations.
More than 90% of Senegal's population is Muslim, mostly Sufis. Up till now the country has escaped jihadist attacks unlike other west African nations.
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