Muhammad ibn Ibrahim, known as Ibn al-Thumna (), was an Arab military leader of the 11th century.
Probably a native of Syracuse, he was a member of the Arab-Sicilian nobility of the city. At the time of the disintegration of the Emirate of Sicily, he was the most powerful qÃÂþid (commander) on the island.
Around 1050, during the civil war between the various qÃÂþid of Sicily, he defeated and killed in battle Ibn al-MaklÃÂtë, the qÃÂþid of Catania. He later married Ibn al-MaklÃÂtë's widow, thereby usurping control of the city of Catania.
He came into conflict with his brother-in-law, Ibn al-ḤawwÃÂs, lord of Castrogiovanni (modern-day Enna), a city he attempted to attack, but was defeated in battle by the forces commanded by Ibn al-ḤawwÃÂs.
At the end of February 1061, he traveled to Mileto to meet Roger I, to whom he swore allegiance and promised his support to the Normans against the muslims in Sicily, giving one of his sons as a hostage.
The first Norman attempt failed, and Ibn al-Thumna had to retreat and barricade himself in Catania. However, a few months later, the Normans, led by Robert Guiscard, captured Messina and, combining their forces with those of Ibn al-Thumna, defeated Ibn al-ḤawwÃÂs after besieging Castrogiovanni for a month.
The following year, in 1062, Ibn al-Thumna arrived near Entella with the Norman warriors, but fell into a trap set by a group of Sicilian-Arab townsmen, who lured him under the pretext of peace negotiations and, seeking revenge for his betrayal, assassinated him.