Meanings of the Term Oikoumene

Oikoumene (Gr. οἰκουμένη‎) was not only a political and religious term, but first and foremost a geographical one. The Greek word οἰκουμένη‎ means “inhabited,” a participle to which the noun γῆ‎, “earth,” is implied.¹ Literally, oikoumene is the “inhabited earth.”

We do not know who coined this term. The geographer Agathemeros, writing during the Principate, attributed it to Anaximandros of Miletus (c. 610–547 bce),² but the context suggests an anachronistic use of the term. Herodotus, whose Historiae were published in the last quarter of the 5th century bce, is our oldest source for the word oikoumene in a geographic context (3.114: χώρη ἐσχάτη τῶν οίκεομένων χωρῶν‎, “the furthest country of the inhabited countries”). Of course, the scarcity of sources does not allow us to fix a certain date, but the uncommon use of chora instead of ge in Herodotus makes it plausible that oikoumene was not yet a fixed term.³ We may include here a dubious fragment of Xenophanes (c. 570–467 bce?), which informs us that “at certain times the disc of the sun is relegated to a certain part of the earth which is not inhabited by us” (DK 21 A 41a: ἀποτομὴν τῆς γῆς οὐκ οἰκουμένην ὑφ‎´ ἡμῶν‎).

What is, then, the meaning of the term? Seemingly, it was used to differentiate between inhabited and uninhabited parts of the world.⁴ Hence, some scholars have guessed that it was first used when the Greeks encountered large unoccupied spaces during the Great Colonization. But the west, east, and north were considered populous areas, since the Celts, Scythians, and Indians lived there (e.g., Ps.-Scymn. 170–82). The Greeks of the Archaic period knew little about the Sahara and other wastelands. By contrast, the traditional view, attested as early as Homer and Hesiod, was that the world was populated from the centre out to the edges of the Earth, surrounded by the Oceanus.⁵

Therefore, it is likely that the term oikoumene originated in another context. As early as 500 bce the philosophical schools of the Pythagoreans and Eleates claimed that the Earth is not a disc but a globe.⁶ Parmenides, the founder of the Eleatic school, is even credited with astronomical and geographical research. For example, he divided the surface of the Earth into zones or belts (gr. κλίματα‎), which run around the globe. According to this view, there are five zones, two inhabited and three uninhabited. The details of Parmenides’s system—like those of so many of the Pre-Socratics—cannot be reconstructed completely, not the least because Aristotle, our main source, propagated his own theory of zones. But the basic outline may have looked somewhat like Figure 1. The limits of the zones are generated by projection of the course of the sun and of circles of latitudes onto the globe. The middle “hot” or “scorched” zone has its boundaries in both tropics (c. 24°)⁷ and is divided by the Equator. The two temperate zones extend from the tropics of Cancer and Capricorn to the north and to the south up to the so-called Arctic and Antarctic circles (c. 66°). Between these circles and the poles there are two cold zones (see, e.g., the description in Strabo 2.5.3, C 111). Only the two temperate zones were considered habitable; the others were perceived of as uninhabitable owing to excessive heat or cold.

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Figure 1. The five zones of the Earth according to Parmenides.

Illustration by author.

Parmenides’s hypothesis that there are not one but two zones where people can live, one in the Northern and one in the Southern Hemisphere, was revolutionary. For the first time, the idea that huge parts of the Earth were unknown and inaccessible to the Greeks was enunciated.

After the invention of the globe-Earth theory, a new term was needed to distinguish the known parts from other, but theoretically habitable, parts of Earth. For this purpose, the word oikoumene was coined. If the fragment of Xenophanes cited above is authentic, we have another hint that oikoumene was originally used in an astronomical context. Furthermore, the first discussion about the form and extension of the oikoumene in Aristotle (mete. 2.5, p. 362b13) uses astronomical ideas and terms.⁸

The Concept of the Oikoumene in Early Geographers

The model of the Earth with five zones was widely accepted until the end of antiquity. Aristotle’s authority and the elegance of Aratus’s and Vergil’s poems made it popular among the literati, although Greek and Roman geographers knew it did not always correspond with reality: neither was the zone around the Equator totally scorched, nor were the areas in the north of the Arctic Circle unbearably old and uninhabited, as had been had documented by travellers’ accounts. But the inherent schematism of the model turned out to be too convincing, and theory trumped autopsy.

During the 5th century bce and the first half of the 4th century, the globe-Earth theory of the Pythagoreans and Eleates prevailed over the Ionic model of the flat Earth. It was a long-lasting fight which was basically decided among the intellectuals at the time of Plato and Aristotle,⁹ but went on among some groups—such as the Epicureans—during Hellenistic and Roman times and popped up again in late antiquity with Christians (e.g., Kosmas Indikopleustes) who rejected some aspects of the globe theory because of its incongruousness with some biblical passages.

After realizing that the surface of the Earth was only partly inhabited and known by men, Greek geographers were faced with new questions: Was there only one oikoumene, or more? How did “our” (Gemin. elem. astr. 16.3) oikoumene fit into the northern temperate zone?¹⁰ How big was the “inhabited world” extending from the Pillars of Heracles in the west to India in the east? Such questions of the size, form, and position of the oikoumene(s) were hotly debated in the 4th and 3rd centuries bce. The Greeks between the times of Democritus and Eratosthenes found different answers to these questions. Especially popular among literati became the model of the historian Ephorus (c. 405–330 bce), who drafted the oikoumene as a rectangle in the fourth book of his Histories (Strabo1.2.28, C 34; Cosm. 2, p. 148; see Figure 2, where the south is oriented to the top). Ephorus equated every corner of his rectangle with astronomical points and every side with both winds and peoples: the Scythians lived in the north, the Celts in the west, the Ethiopians in the south, and the Indians in the east. The model revived the old notion that Greece (or rather the Aegean) lay in the middle, and it was compatible with the prevalent Hellenocentric idea that normalcy and civilization are to be found in the middle, while the environment towards the edges becomes increasingly barbaric and archaic. Geographers of the 4th and 3rd centuries bce tried to combine and improve on these two basic models. All conceived of the oikoumene as a rectangle, and for the ratio between the length (from east to west) and the breadth (from north to south) Democritus proposed 3:2, ¹¹ while Eudoxus had 2:1,¹² Aristotle “more than 5:3,”¹³ and Dicaearchus¹⁴ 3:2. Our sources do not, unfortunately, inform us how the geographers arrived at their conclusions. Only for Eratosthenes of Cyrene (276–194 bce),¹⁵ the most influential geographer before Ptolemy, may some hypotheses be advanced.

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Figure 2. Ephorus’s rectangle.

Illustration by author.

The Oikoumene of Eratosthenes

With regard to the division of the oikoumene, Eratosthenes agreed with his predecessor Dicaearchus, who invented a “diaphragm.” Intersecting the whole Mediterranean and continuing with a mountain range (“Tauros”), this divides the oikoumene into a northern and a southern part. By adding up the measurement data found in travellers’ accounts, periploi, and itineraria, Eratosthenes reckoned its length at 77,800 stades, and its breadth at 38,000 stades, finding a ratio of “more than 2:1” (Strabo 1.4.5, C 64; Agathem. 1.2 (GGM II 471); cf. also Gemin. elem. astr. 15.4; 16.5.). The subdivision of the northern and southern parts of the oikoumene followed morphological breaks such as mountain ranges or major rivers (e.g., the Indus forms the boundary between India and Ariane). Hence Eratosthenes’s system was not an abstract grid (like the later one of Ptolemy) but a net of some¹⁶ major meridians and parallels. The most important nod was at Rhodes (see Figure 3). Eratosthenes also tried to subdivide the bigger sections (which he termed sphragides, “seals”) into smaller parts. Like the cartographers of early times, he often used geometrical shapes (e.g., Britannia as triangles, India as a rhomboid, the Caspian Sea as a circle) or easily recognizable images (e.g., Mesopotamia as a galley, Sardinia as a footstep, the Peloponnese as a plane-tree leaf).¹⁷ Through these, the form of the oikoumene was easily constructible, measurable, and memorable. Eratosthenes’s sketch of the oikoumene remained the master model until the time of Ptolemy, and even Hipparchus subscribed to it despite some criticism. Dionysius Periegetes, who wrote a didactic poem on geography in Hadrian’s time, used Eratosthenes’s Geographika to a large extent, regardless of some modifications.¹⁸ Dionysius’ work itself was translated by Avienus and Priscianus into Latin, thus establishing this concept for a Roman audience as well.

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Figure 3. The oikoumene according to Eratosthenes of Cyrene.

Illustration by author.

The idea that other oikumenai can be found on the surface of the Earth was often discussed in Hellenistic, late Republican, and early Imperial times, but took a back seat in later times (possibly because of the Roman concept of imperium sine fine). Marinus of Tyre and Ptolemy, who collected all the geographical information of the early 2nd century ce, no longer conceived of the oikoumene as an island in the Ocean (or as surrounded by interconnected seas like the Atlantic). On Ptolemy’s world map, which covered a space of 180° in length and 80° in breadth, an “unknown land” (agnostos ge) extended even farther to the north and south.

Since Eratosthenes likened the shape of the oikoumene to a “chlamys” (the Macedonian cloak),¹⁹ he may have alluded here to a new—political—dimension of this term.²⁰ We find such a view expressed for the first time in the dictum of Demetrius of Phalerum (c. 360–280 bce) that he wanted to make Alexandria the “capital of the oikoumene,”²¹ and according to Athenaeus (12.536a), the Hellenistic king Demetrius Poliorcetes was depicted as “riding on the oikoumene” in an Athenian painting (c. 290 bce).²² But it was especially the Romans who, after their victories over Antiochus III in 189 bce and Perseus in 168 bce, could present themselves as the masters of the world. Polybius, trying to explore the reasons why the Romans “nearly” subjected the whole oikoumene to their rule (cf. 3, 59; 15, 9, 5; 6, 50, 6, without this qualification), recorded this idea for the first time.

Orbis terrarum

For the Greek oikoumene, the Romans used the compound orbis terrarum (or, less frequently, orbis terrae). It is first attested in the memoirs of the Roman Stoic and consul P. Rutilius Rufus (c. 158–78 bce). Since it is not a verbatim translation of the Greek term,²³ Rufus probably coined it as a catch phrase to underline the vastness and greatness of the imperium romanum. ²⁴ According to Plutarch (Ti. Gracch. 9.4), it was already Ti. Gracchus who styled the Romans masters of the oikoumene. This political slogan is quite often attested from the time of Sulla (Rhet. Her. 4.9.13 et al.). It was amplified and elaborated during the Principate (the canonical view is expressed in Verg. Aen. 1.279: imperium sine fine; cf. also 6.851; Ov. Fast. 5.93, etc.). Augustus’s claim was that “he subjected the oikoumene to the rule of the Roman people” (RGDA 1: orbem terrarum imperio populi Romano subiecit). Later, Nero was called “god and saviour of the oikoumene” (SIG 666.3; 668.5); Marcus Aurelius became “benefactor and saviour of the oikoumene” (SGU I 176,2).

It was not only the political power in the Mediterranean that shifted to the Romans. Earlier, Olympus, Delphi, Athens, and Alexandria had in succession been considered as centres of the world. Now, however, the city of Rome was heralded as the undisputed caput orbis terrarum and, from the reign of Nero, even as caput mundi (Luc. Phars. 2.655). Quite often we hear about another oikoumene or an alter mundus in Roman times, being an indication not only of the growing spatial knowledge of the Romans but also of the political and military ambitions (e.g., Paneg. Messalla 79; Iust. 41.1.1; Tac. ann. 2, 2, 2, Flor 1.45.16).

The older view of the Earth as flat disc lingered on in Latin texts (except in scientific contexts, e.g., Cic. Nat. D. 2.164; Sall. fr. 3 Maurenbrecher), since the word orbis evoked the notion of a circle.²⁵ Enyclopaedists like Pliny the Elder and especially Isidore of Seville,²⁶ poets like Dionysius Periegetes, Avienus, and Priscianus, and even geographers like Strabo have long panoramic descriptions of the oikoumene, emphasising not only the topographical but also the cultural aspects and details.

The Christian Oikoumene

The Christian idea of the oikoumene²⁷ in the New Testament probably derived from the Stoic view of the world as a space inhabited by people of the same nature. According to Matthew 24.13, “the gospel of the kingdom shall be preached in all the inhabited world (oikoumene).” The evangelization and establishment of a “Catholic” church was aimed at the whole world (Martyr. Polycarp. 8, 1). Lactantius (c. 250–325 bce) could already talk about “our” orbis/oikoumene (inst. 3.23.15), a compound which was probably coined as a parallel to “our sea” (mare nostrum). The first Council of Nicaea (325 ce) was called an “oikoumenical synodos,” since it aimed at uniting all of Christendom (Euseb. vit. Const. 3.6). In the year 444, Dioscourus of Alexandria was addressed for the first time as oikoumenikos patriarches. Despite the objection of Pope Gregory the Great, the title remained with the Patriarchate of Constantinople.²⁸