GSM: A Lesson for Beginners, by a Beginner

Composing a text for a website such as this requires a balancing act between the website’s likely readership. Some readers will be highly skilled in the field of digital humanities as it relates to Islamic Studies while there may be others for whom this may be one of their first experiences of the field. As such, although experienced with various aspects of digital humanities that I could discuss, I thought that for my first post I would do something that was completely new for me.

Most of my previous work within Islamic Studies DH has been related to matters textual, including OCR, text mining, and XML files. What it has never encompassed is matters spatial, such as using GSM techniques to better understand the past. As such, in this post I shall go through the process of doing this for the first time.

While my research is primarily focused on Christian-Muslim relations in the lands of Egypt and the region of al-Sham during the period of the Crusades, a recent project has focused on the islands of Malta in the early seventeenth century. At this time, the islands were ruled by the Knights Hospitallers, who used to go on plundering naval raids against Muslim (Ottoman Turkish or North African) shipping or coastal communities around the Mediterranean. In so doing, they brought many Muslim slaves back to the islands, where they were set to work building the fortifications in Valletta or as rowers on the Knights’ galleys.

The Muslims slaves are primarily known to us from their appearances at the Maltese tribunal of the Roman Inquisition, where they could be put on trial or called as a witness. The project I have been working on examines the 1605 trial of one Muslim slave, Sellem b. al-Sheikh Mansur, who was accused of practicing magic, and where a number of other Muslims either appear or are mentioned. In these appearances, the slaves’ hometowns are mentioned, and so it is possible to map their origins. I have used the slaves from that trial and from the 1598 trial of a man named Georgio Scala, who pretended to be Christian but was really Muslim (published in Georgio Scala and the Moorish Slaves, ed. D.A. Agius, Malta, 2013).

Muslim slaves appearing in the trial record of Archives of the Inquisition on Malta Processus Criminali 26A, ff. 260r-346v (the trial of Sellem b. al-Sheikh Mansur, 1605):

Name of slaveOriginReference in document (folios)
Muhammad ShamiSyria324r

Muslim slaves appearing in the trial record of Archives of the Inquisition on Malta Processus Criminali 16A, ff. 76r-123v (the trial of Georgio Scala, 1598):

Name of slaveOriginReference in document (folios)
Georgio ScalaDamiettathroughout
Habd IracchmenSyria93v
Unnamed slaveSfax90r
Bu TayyibSfax97v

Creating a simple map of the origins of Muslim slaves on Malta c. 1600, from these two documents

First, using the information listed above, I created a dataset using MS Excel, listing the places of origin in one column and the number of times those places appear in a second column:

I then saved it as a XLXS file.

Next, I went to GoogleMaps’ MyMaps feature (, for which a Google account is required:

Then, I selected ‘Create a new map’, and this screen appeared:

Then, under the ‘Untitled layer’ feature, I clicked on ‘Import’, and used the resulting screen to import the Excel dataset I had previously created.

The map was automatically created:

This map now allows the viewer to see where the slaves originated on a GoogleMap, with the markers showing the number of slaves from each place linked dynamically to the icons in the box to the left of the screen. It would be useful if it were possible to change the size of the markers to reflect the numbers of slaves (so that, for example, the marker at Sfax was the biggest to highlight the fact that a larger number came from there than anywhere else), but it does not seem possible to do this, currently.

Finally for this map, I searched for Malta using the main search bar in the map, and this automatically came up in the map:

The above exercise and the resulting map is useful in highlighting not only where the slaves on Malta came from but also, by extension, the direction of the raids made by the Knights. It is noticeable, for example, that they were almost exclusively south and east, against Ottoman territory. The territory that forms the modern state of Morocco, on the other hand, seems to have been left by the Knights (as, indeed, other historians of Malta have also surmised). 

So, a map that is simple to create but which is visually striking and allows for comparatively easy interpretation of the data.

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