The Manuscript

The Tabula Peutingeriana or Peutinger Diagram is a chart made in antiquity which shows a swathe of the world stretching from England to Sri Lanka. With more than 3,300 places, rivers, islands, peoples and regions marked, it is the only detailed Latin chart of the world known to survive from the Roman Empire.

For readers accustomed to maps it is hard to get used to, massaging all the countries into a canvas 20 times wider than tall. Landmasses are foreshortened: western Europe is shown at only one-ninth of its Mercator-projection height. Each sea is graphically squeezed down to a crack. Large areas are signified by spaced-out lettering. Some 550 places are additionally represented by icons.

Neither the author nor the date of the prototypic Tabula are known. Based on its emphasis on the imperial Roman religion before Christianity and from the outline of the Empire's outer frontier, it is estimated to have been first published in the fourth century CE. Many of its markings only accumulated later. No original is extant, but three copies enable us to reconstruct it virtually:
  1. Vienna Nationalbibliothek Cod. 324, the Tabula Peutingeriana proper, a 6.7-metre-wide roll-form manuscript copied in about 1200; it is a UNESCO Memory of the World item. A freely accessible online at Richard Talbert's Atlantides section is easier to use, while the library's digitization provides richer detail;
  2. The Ravenna Cosmography, a list of world places drawn up in about 700 CE in extensive reliance on the Tabula, but without distances or a graphic layout. It is preserved in three manuscripts;
  3. Pellegrino Prisciani's sketch in about 1495 of a small part of a chart constructed in the same manner as (1); that chart, then in the bishop's residence at Padua, Italy, is now lost; the sketch is preserved in MS 129, ff 44v-45r at the Archivio de Stato in Modena, Italy.
The original title and purpose of the Latin chart are unknown. Tabula is a Latin term for a chart, diagram or book figure and the instantiation refers to a former owner of (1), Konrad Peutinger. Hypotheses that the chart was intended to be a road map, a military map, a tourist map or an imperial wall-hanging lack any firm evidence.

Only in the sense that the London Underground diagram is loosely called a map is the Tabula Peutingeriana (hereafter TP) cartographic. Axes of communication are presented with the greatest clarity, akin to the way people explain a journey by gesture, whereas locations and distances are simplified and thus distorted. Such topological diagrams are not maps; to assist their work of visualization, their scales may be variable and even their compass directions will be out of sync.

After its rediscovery in the 1490s, the diagram principally interested historical geographers seeking the names and locations of ancient places and roads. Only since the 1980s has the growing field of historical cartography seriously tackled the question of how the TP was made and why it differs so radically from the second-century-CE scientific chart of the world in Greek by Ptolemy of Alexandria.

The realization that neither the Roman public and military administration nor private travelers in the ancient west generally used maps raises the likelihood that the original chart-maker's motives may have been private and his design skills self-taught. The TP may have been astonishingly novel to its readership at the start and refreshingly different even from those world maps alluded to in late antique literature, which generally appear to have been mappae mundi, starkly schematic visualizations of Europe, Asia and Africa on an oval canvas with just 100 or so places named.

The communication lines marked on the TP are saw-toothed and drawn in red, with each place name along the way written inside the teeth or chicanes. These are the TP's standardized symbol for any fixed settlement, from a great city to a desert staging post. Contrary to the common assumption that these lines signify paved roads, it is clear they have been variously obtained from travel itineraries, shipping logs and plans of fortifications. Basically they represent axes with a variety of human uses, and only with additional evidence should any one of them be treated as a road.

The schematic diagram's designer skillfully reduced a mass of information about the whole known world to just one aspect: which places are "along from" other places of similar longitude and how far apart these are, generally in Roman miles along some walkable or navigable route. The TP largely omits north-south arteries of communication. Places on the same global meridian sometimes end up far apart.

Efforts to reconstruct the proto-Tabula begin with the assumption one or more sheets are missing from the left edge of (1) and that its graphics are often in error by fault of copyists, whereas (2) has many faults, deliberately omitting pagan places and containing many gross spelling errors. In the work of reconstruction, the scholar must identify Christian and medieval additions to strip them away, while archaeological evidence of cities and roads helps to unwind the graphic errors and restore routes that are now occluded in (1) by drawings of city personifications and walls.

The diagram is a landmark in the early history of visualization, reshaping its data for a human point of view and exploiting the full range of Gestalt principles of perception: the routes and coasts are drawn without gaps, achieving good continuity; routes are drawn parallel and in proximity to form groups; the empty blue-green of the seas establishes them as the ground against which the busier land figures; the regions obtain visual closure by being marked across their breadth with large lettering, which in turn stands out by its sharp dissimilarity from the small place-name script.

The TP offers stark evidence that information visualization made major advances in late antiquity, long before the cartographic revolution in sixteenth-century Europe. The diagram is also an indicator of ancient knowledge. The inclusion of the Persian Empire, India and a one-word reference to China indicates for example that western scholars in antiquity were informed, though not very well, about those regions.

Principal resources for interpreting it are Richard Talbert's book Rome's World and the associated database and map set (2010), Konrad Miller's Itineraria Romana (1916) and the Tabula Peutingeriana Animated Edition (2018). The blog you are now reading exists to annotate the latter.

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