Mompracem's existence is confirmed on old maps and globes from the early 16th century to the 19th century as a large island in a rather prominent position. However, the situation varies: Either it is close to the island of Labuan or somewhere in the ocean off the north-west coast of Borneo and thus far away from Labuan. On maps of the 20th / 21st Century does not appear. Therefore, for a long time it was assumed that the island's name came from Emilio Salgari's fantasy. Salgari used a map by Friedrich von Stülpnagel, who published a map of Southeast Asia in the first four editions of Stieler's Hand Atlas (1831 - 1864), among other things. On Stülpnagel's map, the island of Mompracem is about 120 kilometers west of Labuan.
Robert Nicholl (1976: 104), who has dealt intensively with historical maps of Southeast Asia and especially Borneo, identified Mompracem with today's island of Keraman (Kuraman) because of its strategic location. This island is located just about five kilometers southwest of Labuan and in its immediate southern neighbourhood are the smaller islands of Rusukan Besar and Rusukan Kecil (large and small Rusukan). So the location of the island does not fit the description of Salgari. Spagnol (1982: 160) recognized that the maps that Salgari consulted were second-hand information and that this explains the mistakes he made. In fact, the mistake was made in the passing on of the map material. Therefore, we have to look into the history of map making in relation to the North Bornean area.
The Portuguese were the first Europeans to visit Brunei frequently in the 16th century, and this area near the Brunei Bay was well mapped by them. They were looking for a trade route to the Spice Islands (Moluccas), this route led past the north-west coast of Borneo. They often stopped in Brunei, as Nicholl well documented in 1975. It was important to the navigators that the maps were reliable for the location of islands and shallows. In addition, they were so valuable that they were not allowed to be taken out of the country. Because the trade in spices was very lucrative, these cards were guarded as a great treasure so that no other European sea power should dispute this trade. However, it happened again and again that material was disclosed and copied by other cartographers.
The Portuguese drew Mompracem exactly where Keraman is today. Sometimes they just marked Mompracem by name and left the actually larger neighboring island of Labuan unnamed, because Mompracem was very important for navigational reasons: From here they had to turn east into the Bay of Brunei, so it was a prominent signpost for them.
The name of the island varies, including Mopiasem, Mopalaca, Mopracam and Mon Pratem, but the name Keraman does not appear at all. Labuan, too, had a different name on Portuguese maps, namely "Pulo Tigao". Pulo (pulau = island) Tigao and Mompracem are always next to each other - like Labuan and Keraman later. Both Pulo Tigao and Mompracem are consistently drawn in by the Portuguese who were there, lying in front of the Bay of Brunei. Nicholl points out in his 1976 cartography study that the Portuguese maps remained unsurpassed for 200 years.
The Dutch, who were also very interested in the spice trade, tried early on to get hold of the valuable maps, which only succeeded illegally and was partly passed on via hearsay. The Flemish geographer Ortelius published a map as early as 1574, which is very rudimentary and flawed, especially as far as Borneo is concerned. For example, the name of the highest mountain Kinabalu in the state of Sabah is next to a group of islands south of Borneo, the island of Natuna is where Labuan should be, and "Mompiasti" is roughly at the height of Gaya. One of the best-known cartographers, Gerardus Mercator, took his bearings from Ortelius, later Hondius resorted to the material of the two. The position of the island appeared in different positions.
Johannes van Keulen's map: "Nieuwe Afteekening van 't Eyland Borneo" (1740)
Altogether there were two different traditions concerning the location of the island of Mompracem: as a neighboring island of Labuan or as an island somewhere further away from Borneo, often as a field with dots. The Dutchman Johannes van Keulen probably noticed this discrepancy and tried to solve it by drawing the island of Mompracem twice on his map "Nieuwe Afteekening van 't Eyland Borneo" (1740): once as the island of Monpracem and once as the shoal Monpraly, in in the immediate vicinity of the island of Monpracem. You can see "Pula Tigaou of Victoria I." on this map, which in turn is Labuan. To the south of it is Mompracem, the name appears directly under the island of Labuan. Mompracem is a much smaller island here than Labuan. To the south of the island there are two small islands, these are today's Rusukan Islands. These four islands form an "island image" that is typical for me, which often appears on the maps and corresponds to the current arrangement "Labuan - Keraman - Rusukan Besar - Rusukan Kecil". Directly afterwards to the south you can see a second signature on the map from 1740, which reads: "Momprahy" or "Momprasty". I can identify the first six and the last letter, in between there are one or two other letters that are difficult to read, so "MompraXXy". It is noticeable that this signature is in a field - written across it. If you look at the location, "Mompracem" corresponds to the location of the island of Keraman, while "MompraXXy is located opposite the Brunei coast between Kuala Baram and Muara. The field shown indicates a shoal. In fact, one has on later maps often a dashed line / oval shape with the name Mompracem.
The Dutch assumed dominance in Southeast Asia and the spice trade at the beginning of the 17th century, but they did not visit Brunei and Borneo's west coast, except for the visit of Admiral van Noort in 1600. As a result, they copied the islands and names northwest when they made their Southeast Asia maps -Borneos. They could not draw on their own experience from their seafarers or traders. The many errors are explained by copying and the lack of insight on site.
Map makers from other nations such as the French and the Germans also produced maps and atlases on Southeast Asia and, since they were not on site themselves, used the usual maps of the Dutch, mostly maps in the tradition of Ortelius and Mercator. This continued into the 19th century, and Mompracem is mostly placed somewhere in the sea.
In order to determine the location of Mompracem, one should concentrate on the Portuguese maps. It was not until the British began again in the 19th century with cartography based on local experience (exception: John Jesse from the Trading East India Company was there in 1775). With the treaty of 1824, the British and the Dutch devided Southeast Asia into their spheres of influence. Today's Indonesia goes back to the Dutch possessions, Malaysia to the British ones. The island of Labuan was annexed by the British in 1846. The Admiralty had already visited this area a few years earlier to support James Brooke, who lived in Sarawak from 1840 and was confirmed as a white rajah of Sarawak by the Sultan of Brunei in 1842 (by gun policy). On the maps of these British people who were involved in the affairs in Borneo, the island southwest of Labuan, which formerly the Portuguese named Mompracem, was now called Keraman or Kuraman. The names Mompracem and Keraman do not appear on any card at the same time, nor do Pulo Tigao and Labuan. Pulo Tigao is called Labuan on British maps. The position of Pulo Tigao and Mompracem on Portuguese maps corresponds to the position of Labuan and Keraman on the British maps. Since Pulo Tigao was later called Labuan, it is logical that Mompracem became Keraman.
Both the Portuguese and the British were there and made reliable maps for their seafarers, so it can be assumed that the Portuguese referred to that long island southwest of Pulo Tigao (Labuan) as Mompracem, and the British referred to the same island as Keraman.
In 1883 Emilio Salgari worked with a - non-Portuguese - map that Mompracem mentions - in the position far from Labuan. Incidentally, he mentions the island of Keraman in the novel "La Riconquista del Mompracem" (1908): Yanez drives the route between Labuan and Keraman here. But since there is no map that mentions both islands by name (Mompracem and Keraman), Salgari probably used another additional map in 1908, one that called the island Keraman and no longer Mompracem. Salgari may never have known itself that these two islands were identical.
Noort, Olivier van: Description du pénible voyage faict autour du Globe Terrestre par Sr. Olivier du Nort d'Utrecht. Amsterdam 1602.
Aktuelle Karte von Labuan und den umliegenden Inseln
Detail of a map by Hermann von Stülpnagel