Although this is speculative, we have long considered "Organa" in European planispheres, portolan charts, and maps to have been a reference to Kanem and Borno. Some consider "Organa" to have been Ouargla in the Sahara, but the inscriptions in maps from the 1300s and 1400s suggest Kanem and Borno. The strongest evidence of this identification is the Latin inscription from the 1339 portolan chart of Angelino Dulcert. To our knowledge, this is the earliest European source to use the toponym of Organa. But whats makes its identification as Kanem more likely is the Latin inscription's reference to naked black populations attacked by Organa's Saracen king. Moreover, these peoples allegedly lived by a sea. The best candidate for this area is therefore Lake Chad, where we know the rulers of Kanem occasionally engaged in wars or raids with non-Muslim societies near Lake Chad.
Indeed, the Latin inscription for Organa reads, "Iste rex Saracenus permanet senper in armis cum Saracenis maritimis, scilicet cum una tera Nigroom qui senper vadunt nudi et sine aliquo vestimento." The French translation of De la Roncière rendered this as "Ce roi des Sarrasins demeure toujours en guerre avec les Sarrazins des bords de la mer, c'est-à-dire avec les nègres qui vont toujours nus, sans le moindre vêtement." The "tera Nigroom" is likely a reference to a "black land" or "land of the blacks," but also close to a sea or body of water. The best candidate for this is Kanem, although it is possible a Saharan region like Ouargla was confused with Kanem further south. To strengthen the identification of Organa as Kanem, one can also note that its position east of Mali and south from Sicily onward points toward the Lake Chad area.
But in 1339, other sources do speak to the kingdom of Kanem engaging in wars or raids against "black" people who lived near a large body of water. According to Dierk Lange's chronology based on the Diwan of Kanem-Borno, there was a king named Kuri Gana (Kuri the Younger) who reigned in c. 1339. This king was said to have died in war with the "Sao" at Ghaliwa, possibly Ngala. This king's name in Kanuri was produced in Nachtigal's list in Sahara and Sudan of Sayfawa maiwa as Kure ghana Ben Abd Allah, dated to 1350. Since Lange's chronology "works best" for the Sayfawa, a date of c. 1339 seems more likely. This date also happens to be around the same time that Dulcert's portolan chart listed a place called Organa. Consequently, one wonders if the name of Kanem's mai, Kuri Gana, was perhaps deformed into "Organa" across the Mediterranean. Then, Kuri Gana's name became the established name for the toponym representing the Kanem/Borno areas.
Exactly how the initial letter was dropped is unclear, but the idea of a Saracen king fighting "naked" dark-skinned people by a sea might match Kuri Gana and the Sayfawa. After all, the Diwan attributed the death of Kuri Gana and 3 other maiwa to wars with the "Sao" in this period. Moreover, if one follows Palmer in Bornu Sahara and Sudan, Kuri Gana (named Kore al-Saghir here) died at N'geliwa, in the area of Marte. This area in the 1300s would have been closer to the shores of Lake Chad and perhaps explain why reports of a "Saracen" king fighting "black" people without clothes by a sea reached Dulcert. Since it is unlikely that areas near the Mediterranean coast would have been defined as a "black land" (perhaps based on the Arabic term for the land of the blacks), Kanem and the Lake Chad region are the best fit for "Organa" in 1339.
The next step to confirm this pet theory would be to examine subsequent mentions of Organa in the 1300s and 1400s European cartographic corpus. Understanding how the name Kuri Gana would have been pronounced in 14th century Kanembu or the routes through which it was deformed in Arabic and Latin are additional necessary steps. Resolving the later conflation of Organa and Ouargla (or another Saharan region) is also necessary. More importantly, if the toponym Organa really was derived from the name of a Kanem king who reigned at the end of the 1330s, it would partially confirm the maiwa of this era engaging in wars with the "Sao" on the other side of Lake Chad, in Borno. Our theory might also have more merit than the often playful and inventive linguistic wordplay and reconstruction of Palmer.
That said, the Kagha (origin of the term kaigama) seems like a reasonable contender, too. The word Kagha seems to have been established in medieval Arabic sources by the end of the 1200s for designating part of Borno (Jaja, Kaka, Kagha). But how that transmogrified into Organa is unclear. The Kuri Gana or Kore Gana etymology we proposed may explain the appearance of the "gana" part of "Organa" but also requires dropping the initial k and a vowel.