New publication: The Periplus of the Erythraean Sea: A network approach

The Periplus of the Erythraean Sea is a Roman period guide to trade and navigation in the Indian Ocean. Justly famous for offering a contemporary and descriptive account of early Indian Ocean trade, the work has been subject to and a point of departure for numerous studies. Its extensive influence on scholarship is, however, also problematic, as it reflects the limited information and cultural and personal bias of its unknown author. Network analysis allows us to map, visualize and measure interconnectedness in this text. Many of these connections are not explicitly mentioned in the text, but by connecting not only places with places, but also products with places that export and import them, we get a partly different impression of Indian Ocean trade from that conventionally gathered from the Periplus. It allows us to ask questions about the relationship between coastal cabotage and transoceanic shipping, to identify regional trading circuits, and unexpected centres of long-distance exchange.

Asian Review of World Histories // Volume 4, Issue 2/JULY 2016, pp. 191-205

Zoomable figures and dataset are available from Bergen Open Research Archive

Meanwhile in Bergen...

It's been too long since I updated this blog, which does not, however, mean that we have been idle. Here is a brief report on some of the things that has happened since May and that will take place over the next few months.

In late May I went to Singapore where I organised a panel at the Asian Association of World Historians  together with Japanese colleagues Masaki Mukai, Hisatsugu Kusabu, and Yasuhiru Yokkaichi. The session was called Pax Romana and Pax Mongolica: New Approaches to the Anatomy of Pre‐modern Martitime Networks (session 4.3 in the program) and proceedings will eventually be published in the open access Asian Review of World Histories, pending peer review. The conference gave the opportunity to indulge in one of my other academic interests, namely world/global history, which interestingly looks different from an Asian perspective despite the disciplines aim to transcend old, Eurocentric paradigms of history. For my interest in networks a splendid session was World Maps as Knowledge Aggregators: from Renaissance Italy Fra Mauro to Web Search Engines (session 5.5. in the program) where the panelists discussed renaissance texts and maps as early examples of hypertext, and how modern software can be used to mine them for information.

Summer started with the Sunbelt Conference om Social Network Analysis in Brighton, where I presented on the social networks of so-called client rulers in the Roman Near East (an updated and hopefully improved version of the study I've written about here. This year there was one archaeological session and several on historical networks. Interest in historical and archaeological networks is certainly up only in the two brief years since I attended the Hamburg conference, and the Sunbelt is becoming a great place for thinking about and discussing methodology with people working with other periods and empircal settings, and for engaging with the social sciences in general, a useful exercice for scholars working with distant periods.

Next stop was in Konstanz, where Tom Brughmans had invited me to visit the Network Science group of professor Ulrik Brandes and to give a lecture on a network analysis of ancient Indian Ocean trade based on the Greek merchant handbook known as the Periplus of the Erythraean Sea. In addition to the opportunity to have a critical and constructive discussion of some of my case studies with a group of experts on network analysis and graph visualisation I was introduced to the Visone graph visualisation software, which contains a lot of nice features for historical network analyses, such as animations of time sequences, which will come in very handy for the above study of ruler networks that I need to write out for publication soon.

One of the reasons that this blog has been silent over the summer is that the terrible events in Palmyra, Syria has taken time, attention and energy. I had the privilege of visiting Palmyra every year from 2004-2010, and did my postdoc on a project called Palmyrena: City, Hinterland and Caravan Trade between Orient and Occident (2009-2013). Suddenly and tragically expertise on the Roman Near East became much more relevant than I would ever have wanted it to be, and some of my time and much of my attention over the last months have been directed at trying to get information on what has been going on, and telling anyone who cares to listen what Palmyra is and why Palmyra is important. Some of this can be found under media on the publications and talks page or on my Norwegian language blog. On a more positive note the events of Palmyra prompted me to return to my half-finished book manuscript on the trade of the city. It is now finished and submitted. Depending on publisher and peer reviews I hope soon to be able to reveal how social networks is the key to understanding the rise and fall of the remarkable city in the Syrian Desert.

Håkon has also been busy, presenting his work on the Manichaean community in third century Kellis, Egypt at the Historical Network Research Conference in Lisbon this September. He has some really exciting networks of the economic and religious interaction of this religious minority group, which I hope he'll blog about himself.

Lots of nice things are planned for the next months. I'll be giving two talks on Red Sea/Indian Ocean trade at two different conferences, one on trade in minerals, the other on textiles. In both cases network analysis provides opportunities for integrating archaeological and historical data, and arguably gives a better understanding of the interactive and mutual activity of trade than traditional approaches. In November Professor Nicholas Purcell (Oxford) will visit our research group Ancient History, Culture and Religion. Purcell's work with Peregrine Horden on The Corrupting Sea has been instrumental in the surge of interest in network studies within classical and medieval studies, and I'm looking forward to hear hvis view on where the study of connectivity stands now. There's going to be a NeRoNE project conference in December. I'll post details on that when the abstracts are all in, and last but not least Birgit van der Lans, Groeningen, will come to Bergen for her postdoc on a Niels Stensen Fellowship. Birgit works on Jews and Christian in the Roman Empire, partly from a social network perspective. She will join our research group and also be associated with the NeRoNE project.


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Proto-globalisation in the Indian Ocean World and network approaches

Last weekend I attended the concluding conference of the ERC-funded Sealinks project. The Sealinks group, headed by Nicole Boivin of Oxford University, has investigated the early maritime links that connected societies on the Indian Ocean rim, using primarily evidence produced by archaeobotany, zooarchaeology, genetics and linguistics. Many results have already come out, and these shed light on processes going further back in time and having more profound and lasting impact, than those evident from earlier studies based on artefactual, epigraphic and literary evidence.

The conference gathered researchers working with biological and environmental proxies, along with with traditional archaeologists and the odd historian. Indian Ocean trade and navigation, as well as the  early history of globalisation being among my other research interests, I found the conference immensely informative. It struck me, however, that although almost all presenters used the N-word, there was next to no discussion on what a network is, how past networks can be approached, and what insights this might give. This is not intended as criticism of the work presented, which was generally of very high standard. In fact the observation would be valid for most archaeological conferences I've attended, and I've worked with the Indian Ocean for more than ten years myself before starting consciously to think in terms of networks myself. Indian Ocean connectivity, however, is a subject that would readily lend itself to network approaches, and in this post I'd like to share a few thoughts on how different groups of material might have benefitted from being approached from a network perspective.

Networks of people

My own research on Indian Ocean trade is primarily on merchant networks: how they formed, cohered, operated and interrelated. In my paper in Oxford I argued that merchants from the Syrian city of Palmyra engaged with local and regional social networks of power, ideology/religion and commerce, in the process of expanding their own ethnically based network from the Syrian Desert into Mesopotamia, the Persian Gulf, the Red Sea and the Arabian Sea. Our data on merchant networks are of literary, epigraphic and ceramic nature – the Palmyrene network for instance being attested by circa 50 inscriptions recording the presence or activities of Palmyrene groups and individuals in settings certainly or very likely connected with Indian Ocean trade. Similar data would be possible to utilize for other groups. Ingo Strauch and collaborators for instance recently published more than 200 inscriptions in Arabic, Indic, Ethiopic, Aramaic and Greek script from a sanctuary in the cave of Hoq on the island of Socotra. Many of these should be possible to connect with places of origin, religion, language, and script used, reconstructing the network that intersected at the node of Hoq in a manner that would be possible to approach by the toolbox of Social Network Analysis.

Networks of objects

New inscriptions are occasionally still discovered, but in general, the written evidence relevant to ancient Indian Ocean trade is delimited and finite. The archaeological data available from Indian Ocean settings, however, has exploded over the last two decades, following major excavation projects  and better practices of documenting, identifying and publishing finds. In my opinion, there are cases where distribution patterns are not necessarily well suited for network analyses, as the presence of objects does not always reveal how, when and by which routes and agents they moved from point of origin to find-spot. In the case of the Indian Ocean, however, distribution patterns clearly do have potential for network analyses, as distances, topography and climate led to virtually all communication taking place by sea. Network analysis based on distribution patterns of ceramics, beads and glass – goods that can be traced to place of production on stylistic, chemical and petrographic grounds, could clearly reveal directions, bottlenecks and clustering of trade.

Networks of places

Clearly, the same would be the case with settlements. Attempts at modeling relationships between ports and their hinterlands and between ports, based on size, kinds of imports and exports, period of occupation, distance to other centers, season of navigation etc. might help us think about why some places and some regions were important, while others seem to not to have been taking part in long-distance exchange to the same extent.

Networks of genes

Many of the papers in Oxford were on the movement of crops, animals and people, studied by way of genetic material recovered from archaeological sited. Dispersal of genes was in most cases visualized by phylogenetic trees. This is of course also a network analysis, showing genetic connections between the varieties of crops etc. found in different settings. If sufficient numbers of dated examples exist from a sufficient number of sites, I think these would also be good for showing patterns of prehistoric seafaring.