This article aims at reassessing the beginning of the reign of ‘Ala’ al-Din Kay-Qubad, by far the most famous ruler of the Saljuq Sultanate of Rum (c. 1081-1308), by analysing the ins and outs of the naval expedition that he launched against the Crimean port of Sudak (Arabic: Sughdaq سوغداق / Sudaq سوداق). After noting that this event, though often referred to in sources, has not been investigated so far (except by Iakubovskii in 1927), the author sums up Ibn Bibi’s account and makes an inventory of all the other available sources. The campaign is dated ca. 1220-2, before the Mongols took control of the port (Iakubovskii had proposed a similar date, without explanation). At the same time, the article’s main objective is to resituate this specific event in a global perspective: an expansionist policy that was pursuing economic motives in the first place (the control of commercial roads; the supply of slaves). The author shows that simultaneously with the campaigns launched in the south against Armenian Cilicia for the control of the latter’s trade, ‘Ala’ al-Din Kay-Qubad tried to compete in the north with the powerful kingdom of Trebizond on the latter’s own ground. From this viewpoint, the short-lived occupation of Sudak is an important step for the understanding of the failed assault against Trebizond in 1223 (an event analysed here in full details). “The Saljuq expedition against Trebizond in 1223 may be seen as an extension of their Crimean policy: Having failed to defeat their rival in the Black Sea, they now took the war directly to the Empire of the Grand Comneni itself (p. 148).” At another level, the setbacks at Sudak and Trebizond dim the image of a victorious sultan given by the sources as well as by modern historiography. This article, written in a limpid style, is a model of historical analysis, for the vast scope of the sources (Greek, Arabic, Persian) taken into account, for the thoroughness of their interpretation (the author criticises some of Iakubovskii’s analyses on Sudak and, more recently, by Sukhurov on Trebizond), and also for its effort at contextualising an event so far considered isolated, but giving interesting keys to a better understanding of its historical framework.