1. Anthropogeography

1a. Geographical location

Bosporus is generally considered as the narrowest natural strait continuously used for navigation since Antiquity. It is about 31.7 km long and varies in width from 4.7 km at its N end to a minimum of 0.698 km, between Kandilli – ancient Echaia Promontor (Ἐχαία ἀκρωτήριον) and Aşıyan (with ca. 0.750 km between Anadolu Hisarı – ancient Potamonion, on the modern Göksu Dere – and Rumeli Hisarı – ancient Pyrrhias Kyon/Byzantine Φωνεύς).¹ In midstream, its depth varies from 30 to more than 110 m. It has 12 sharp turns (with a 80° turn near modern Yeniköy, Greek Neapolis, Νεάπολις)² and there are many holes and banks in the ground.³

The “Thracian” or “Mysian” Bosporus separates Europe (with the ancient region of Thrace) from Asia (through ancient Mysia/Bithynia) and the waters of the Black Sea from the Sea of Marmara.⁴ Its epithets distinguish it from the ancient Cimmerian Bosporus which separates the modern Black Sea (ancient Pontus Euxinus) from the modern Sea of Azov (ancient Palus Maeotis) and corresponds to the nowadays Russian Kertch.⁵

The normal upper current in the Thracian Bosporus is directed from the Black Sea to the Sea of Marmara in a south-westerly direction at the ordinary rate of about 2 knots, and parallel to the coast of Europe, towards Büyükdere bay (which it does not enter)⁶ to Kirich point,⁷ half a mile northward of Therapia,⁸ passing over Englishman banks, and washing Kiobashi point;⁹ thence taking a south-easterly direction, it shoots over to the Asiatic shore a little south of Injir bay.¹⁰ From the southward of Injir bay (Lat. 41°7’N., Long. 29°6’E.), it runs along the Asiatic coast as far as Khanlijeh,¹¹ whence it is again deflected towards the European shore, and running at the rate of 5 knots between the two Hissars, or castles, or Rumuli and Anadolu, strikes the western shore of Arnaut point;¹² at this part it has been named the Devil’s current.¹³ Between Arnaut point and Defterdar point¹⁴ it follows the direction of the two shores, with a marked tendency to advance towards that of Asia, till, having passed Defterdar point it directs itself almost entirely towards Skutari. The current at the entrance of the Bosporus, from Skutari, sets strongly over to Old Seraglio point, which divides it into two branches, the southern one falling into the sea of Marmara; the western stream, filling the Golden Horn, rushes up as far as the second bridge.¹⁵

However, the current may change direction under the influence of strong SE winds and an increased amount of water and changes into a whirlpool in the coves, making maneuvering and navigation particularly difficult: thus, the same Black Sea Pilot¹⁶ wards off that “only a general estimate can be given of it for the use of the navigator”.

This surface current was very well known to the ancient Greek navigators entering the Black Sea: one of its earliest literary descriptions appears in Polybius, who used scientific (geographic and oceanographic) arguments to prove the excellence of the site of Byzantium.¹⁷

The second, lower, current in the Bosporus flows from the salty waters of the Aegean to the Black Sea, increasing the salinity of the superior, biotic level of this exceptional, “double layered” sea;¹⁸ however, certain oceanographers proclaim that this deep current returns into the Marmara Sea before arriving into the Euxine, and that it is absorbed by the turbulent surface current.¹⁹ We do not know when it was discovered, but Hipparchus, quoted by Strabo (1.3.12) still thought that “the strait at Byzantium makes no change at all but continues to have its outflow only from the Pontus into the Propontis, and, as Hipparchus reports, even stands still sometimes", so, only the Latin writer Macrobius mentions it for the first time in his Saturnalia, at the beginning of the 5th c. AD.²⁰

The geological history of Bosporus, as an ancient rocky sill created before the post-glacial flood of the Black Sea into the Mediterranean which occurred 7600/8400 years ago, ²¹ or as a valley through which the Mediterranean and the Black Sea exchanged their water surplus in both directions over the various geological eras²² has recently caused a great amount of debate. It is interesting to note that even some ancient Greek historians connected flood myths and folk-tales with the first days of the strait: certainly, at least since the final part of the Classical era, the Aristotelian explanation of the formation of the Maeotis, the Euxine and the Bosporus from water and silting brought by the numerous rivers of Scythia was known in the Greek schools.²³ But the most famous author connected with this theory is, in Hellenistic times (more precisely in the 3rd c. BC), Strato of Lampsacus, who has explained in detail the formation of the Bosporus as an irruption of the fluvial waters which had refilled the Black Sea into the salted Mediterranean.²⁴ An explicit connection between Greek flood-stories and the Bosporus’ irruption is not formulated until the 1st c. BC, when Diodorus Siculus²⁵ notes that local historians from Samothrace had included in their line of argument about the autochthony of the islanders stories about the Black Sea flood.

On the other hand, archaeological traces since the Lower Paleolithic period have been found on both European and Asiatic shores of the Black Sea and of the Marmara Sea and there is more exploration underway in the wooded hills of ancient Thrace.²⁶ So, only further (conventional and underwater) archaeological and geological explorations in the region could verify the age of the Thracian Bosporus, the impact of human prehistoric occupation in the area and, eventually, the existence of other channels, on the European or the Asiatic continent, which allowed for the exchange of water between the Mediterranean and the Black Sea in such remote times.

In any case, the agricultural wealth of the European hinterland in the last thousands of years, the numerous rivers which rise not far away and which flow into this geological channel, the numerous bays and natural harbors allowing access to the sea and easy fishing have always encouraged human habitation to develop here, increasingly until the 4th century AD, when Constantinople became the new Rome, and since the Byzantine times until today, when Istanbul counts more than 11 million inhabitants.²⁷ Except Dionysius of Byzantiumand his maritime periegesis of Bosporus’ shores, we have no other ancient detailed and complete description of this shore. But the 16th century reader of Dionysius, Petrus Gyllius, visited the sites and wrote an interesting treaty about the Thracian Bosporus, proposing valuable identifications of the ancient toponyms with the modern places and insisting upon the maritime-oriented character of the Bosporan settlements.

1b. Etymology of the geographical term

The name was understandable, in ancient Greek²⁸ or maybe Thracian,²⁹ as the “pass” (πόρος) of the “ox” (βοῦς). At least since Aeschylus’ play Prometheus Bound (v. 733-734), the etymology of the straits called “Bosporos” was connected with Io’s mythological wanderings through Europe and Asia.³⁰ If the first of the 5th century BC Athenian dramatists had mentioned the Cimmerian Bosporus among the sites of Io’s periegesis, one century later, Ephorus³¹ has probably related the destiny of the same Inachos’ daughter with the Thracian channel. At any rate, after Polybius’ Histories,³² Io’s connection with the Thracian Bosporus becomes common.³³ Toponyms as ἀκταίΒοσπόριαι, Βοῦς, Βουκόλος, Βουκόλια³⁴or even the coins of the Classical Greek Byzantium attest the importance of the “bovine” myth(s), already integrated into the local tradition before Hellenistic times. Thus, the Heraclean historian Nymphis³⁵ relates the toponym with the historical crossing of Bosporus by the Phrygians, during their migration from Europe to Asia, the “Βοῦς” being just the head of their ship in shape of bull’s head;³⁶ another rational interpretation explained the same name by a supposed ancient custom of the Bosporan dwellers, who would have crossed from one shore to the other with their cattle;³⁷ yet the Athenian historian Phylarchos related in the 3rd century BC³⁸ the same name with the verb “σπείρω”, “to sow”, considering that only the inhabitants of the regions out of the Black Sea were aware of the agricultural techniques in the prehistoric times.

In the mythical chronology, these passes from Europe to Asia, on the shores of the Euxine, preceded the Argonautic expedition to Colchis: among the numerous Argonautic stations which have been identified, in Classical, Hellenistic and Roman times, on the shores of the Thracian Bosporus, the most famous are the “Clashing-Rocks” ('Συμπληγάδες', considered as early as Herodotus³⁹), identical with the “Dark-Rocks” (Πλαγκταὶ or Κυάνεαι πέτραι) and identified with the different sloping rocks at the Pontic edge of Bosporus, in particular, on the Asiatic shore, with the rocks still visible in Kavakoz Bay (near modern Şile)⁴⁰ or with the Eşek Adası (near modern Çayağzı), and with the Öreke taşı (near modern Rumeli Feneri)⁴¹ on the European one.⁴²

1c. Scientific perception

Ancient historians and geographers have treated with great interest this essential crossway of the ancient world:⁴³Herodotus records Darius’ bridge across the Thracian Bosporus and chooses the description of this passage between Chalcedon and Cyaneas, between the Persian and Scythian lands, Asia and Europe, for presenting a sketch of the all the northern Hellenic seas.⁴⁴ His first estimation of the channel length, about 120 stadia (23 km), for a width of 4 stadia (0.76 km), is close to the real measurements.⁴⁵ One century later, the first Greek periplous still preserved describing the shores of the Mediterranean and attributed to Scylax of Caryanda, registers the Anaplous as the European (Thracian) shore of the Bosporus, 500 stadia in length, between Sely(m)bria (still called in Turkish Selivri) and Hieron as well as a medium width of 7 stadia for the strait.

By the middle of the 2nd century BC, Polybius included in his geo-historical digression about Byzantium a geographic (or rather “geo-metric”) presentation of all the adjoining seas, confirmed these measures:⁴⁶ for 120 stadia long, his Thracian Bosporus varies in width from 14 stadia (between Calchedon and Byzantium) to 12 stadia at the mouth of the Euxine, between the Asiatic Temple of the Twelve Gods and the European Temple of Sarapis (the two Hiera).⁴⁷ Later on, at the beginning of our era and only several decades after the Roman conquest of the area, Strabo, the Geographer born in Amaseia of Pontus, offers a more detailed, still geometrical description of the channel.⁴⁸ Leaving the Black Sea at the Cyaneas (which he identifies with two islets, one close to Europe and other to Asia, separated by a channel of 20 stadia and by other 20 stadia from the Byzantine and Calchedonian Temples/Hiera [the modern Rumeli and Anatoli Kavağı]), the geographer counts 50 stadia from the Hiera (once unified by Darius’ four stadia bridge) to the Golden Horn: there are 10 stadia from the Hiera till another narrow part of the channel (which is five stadia large),⁴⁹ 35 stadia before arriving at the Sykai “Under-the Fig-tree” promontory (later Ioustinianopolis, Genovese Pera, modern Galata quarter in Istanbul),⁵⁰ and five other stadia to the famous Golden Horn.

It is this European golf, close to the walls of the Byzantines and extending westerly for about 60 stadia, which interests Strabo, as it has always ensured prosperous fishing to his dwellers and, more generally, the economic superiority of Byzantium upon Calchedon, the prior city founded by the “blinds”. In Latin, the works of Pomponius Mela and of Pliny the Elder are the oldest geographic texts preserved until nowadays: taking advantage of the progress of the Roman geography (and probably of Agrippa’s world map), the encyclopaedist situates Bosporus at 711 miles (= 1052 km) from Dyrrachium and the Adriatic Sea, and mentions Darius bridge at the narrowest point of the strait, 500 paces wide.

During Hadrian’s time, Arrian of Nicomedia inspected the Euxine shore and its province and wrote a complete periplous of the Black Sea: as Herodotus, he indicates 120 stadia between Byzantion and the Asiatic sanctuary of Zeus Ourios. In the same century, Ptolemy of Alexandria⁵¹ establishes the coordinates of Byzantion at 56° Longitude and 43°05’ Latitude and those of an Asiatic, close to Calchedon, at 56° Longitude and 43°10’ Latitude. However, the most important text concerning Bosporus, its geometry and geography, probably contemporary with Ptolemy, remains the work of Dionysius Byzantius, de Bospori navigatione: he also estimates Bosporus’ length just like Herodotus, at 120 stadia; for its width, he agrees with the Periplous of Pseudo-Scylax and with Pliny the Elder, approximating it at seven stadia.

As late as the beginning of the Byzantine period, in the VIth century AD, Procopius of Caesarea⁵² integrated the Bosporus in a global geographic description prefacing his Vandalic War: he estimates its length at 84 stadia and its width at more or less 10 stadia, insisting upon a general shape which recalls the ancient cartographic representations of the strait. Among these, the Tabula Peutingeriana inspired by models of the late antiquity offer a good idea about the importance of this crossing point, through the exaggeration of the representation compared with the general “scale” of the map.

1d. Ethnological data

Before the arrival of the Greeks, at the latest at the beginning of the 7th century BC, the two shores of the Bosporus were inhabited by Thracian tribes. On the European side, are attested, in classical times, the Astai⁵³ but also Odrysians and Saepai, and on the Asiatic side the Phrygians, the Mysians and the Bithynians who have successively occupied this north-western part of Anatolia after their migration, about the 12th century BC, from the lower Danube region. As the toponymy and the mythology of the region shows, from Archaic untill Hellenistic times, Ephesians (Ἐφεσιάτης), Rhodians (Ῥοδίων Περίβολοι), Lycians (Λιμὴν Λυκίων,from Lycian Myra to Myrleion) and especially Megarians (at Byzantium and Calchedon) but also (indirectly attested) Arcadians (through their Zeus Apsasion?), Argians (through Hera Akraia?), Corinthians, and Boeotians have probably established themselves in this region,⁵⁴ where Athenians and Spartans will try to impose their rule in classical times.

2. Historical geography

2a. Colonization on the European shore of Bosporus

The ancient sources are not concordant for the foundation of Byzantion, in the first half of the 7th century BC (or, as the modern historians tend to agree, about 660 BC, after the foundation of Calchedon), by colonists come from Megara, Corinth, Boeotia, Argos, Mycenae, Carystos, Sparta and Athens.⁵⁵ Established upon the promontory edged by the Propontis, the Bosporus and the Golden Horn, the city has taken advantage of the maritime currents which forced all the ships coming from the Black Sea to sail close to its walls and which brought to the Byzantine fishermen large shoals of tuna. Its chora extended, at different moments of its antique history, from Selymbria and the mouth of the river Athyras on the Propontic shore to the north on the Black Sea shore. So, “encircled” by Thracian realms, the Byzantine territory had constantly been threatened by the inland Barbarians.

2b. Topography of the European Bosporus / Anaplous

On the shores of the Golden Horn (ancient Greek Κέρας, later Chrysokeras), the ancient and Byzantine texts allocate several sacred places of Byzantion:⁵⁶ after the three ports of the city and the Bosporios Akra (Turkish Saray burnu), there are the sanctuary of the Earth (Tellus) goddess (Γῆ Ἀνησιδώρα), the Temple of Demeter and Kore, the Temple of Hera and Pluto, the Skironides (Σκιρωνίδες πέτραι, close to the modern Suleiman Mosque), the temple of Athena Scedasios (Athena Dissipatoria in Petrus Gyllius’ description), the golf Melias and the Garden (Κῆποι), the Sanctuary of the Arcadian Zeus (Ζεὺς Ἁψάσιος), the promontory called Μελλαποκόψας (modern Fener), two fishing stations called Ἰνγενίδας(?) and, between the, there was a place called after its abundant ivy. North to the promontory (modern Palat Kapusi?), the Golden Horn ends in the “Putrid Sea” (Σαπρὰ Θάλασσα), where the Cydaros (modern Alibey Suyu) and the Barbyses (modern Kagithane deresi) flow together,⁵⁷ near the ancient city of Semystra, mythical place integrated to the territory of Byzantium and connected (through the nymph Semystra, mother or grandmother of Byzas the Founder) to its creation, Argonautic and Inachid legends. On the opposite, northern shore of the Golf, Drepanon promontory could eventually be identified with the modern Sütlüce⁵⁸ and the Auleon Sinus with the golf at Hasköy. Passing the Sykai (nowadays Galata) promontory,⁵⁹ one returns to the principal strait separating Europe and Asia, dominated by the tumulus of Hipposthenes the Megarian and by the cult place of Amphiaraos.⁶⁰ Further to the North, Dionysius of Byzantium recalls two places called Αὐλητὴς and Βόλος, before arriving at the sanctuary of Artemis Phosphoros and Aphrodite Praeia (for Petrus Gyllius Aedes Dianae Luciferae and Veneris Placidae, probably later replaced by the church of Saint Clara/Kemankes mosque, on the slope called in modern times Mumhane). Not far away from the “Forehead” (Μέτωπον, modern Tophane), there is the sacred place of the Homeric hero honoured by the Megarians, Aias the Telamonian (Αἰάντειον, yet on the modern Tophane), the cliff Παλινόρμικον, where the “sea turns” (differently identified with the modern Fındıklı, Tophane, Salipazar or Sultan Saray), and the temple of Ptolemy II Philadelphus.⁶¹ To continue the series of legendary places, the χωρίον Δελφὶν or Καράνδας and precede Θέρμαστις, Πεντηκοντορικόν, and Τὰ Σκύθου, the place from where a Scythian, called Tauros, left for Pasiphae’s Crete. Further north, one finds an Ἰασόνιον,⁶² a Daphne, a βωμὸςἈπόλλωνος, where the Argonauts have probably sacrificed,⁶³ and a place called in later times Diplokionion (translated into the modern Beşiktaş), before arriving at the places recording different sites of colonization on the Bosporos, a foundation of the Rhodians (Ῥοδίων Περίβολοι, maybe in modern times Çirağan Saray)⁶⁴ and of the Thasian Archias (Ἀρχεῖον, modern Ortaköy). The cult place of the Old man of the sea (Senex Marinus, Γέρων Ἅλιος identified on occasion with Nereus, Phorkys, or Proteus, as he was connected with foundation or Argonautic legends) comes next (on the modern Defterdar burnu).⁶⁵ After several other fishing places (Παράβολος, Κάλαμος, Βυθίας, Βάκα with the Sanctuary of the Mother of the Gods) comes, on the site of the modern Arnavut Köy, the Hestiai promontory (modern Akıntı burnu),⁶⁶ yet another place related to the most ancient history of Byzantium, than a place called Χηλαὶ and the sanctuary of Artemis Diktynne.⁶⁷ It is close to this place, at the modern Rumeli hisarı, where a temple of Hermes was erected, that Mandrokles of Samos built for Darius the first Persian bridge upon the Bosporus.⁶⁸

Back into the local mythology, the text of Dionysius of Byzantium, now lost but used by Petrus Gyllius, mentioned Petra Phidalia (at modern Baltalimanı), Cyparodes, Portus Mulierum,⁶⁹ the temple of Hecate Trivia (modern Emirğan) and the Sinus Leosthenes (called in later times Sosthenes and in contemporary Turkish Istinye).⁷⁰ In this same region belonging, in the Argonautic myth, to Amykos, there are also Commarodes (later Νεοχωρίον, modern Yeniköy), Thermemeria, Portus Pitheci, Sinus Pharmacia (modern Therapia)⁷¹ and the steep shore of Clavis Ponti (modern Kireç burnu) and Petra nominata Dicaea.⁷² Following the shore of “Deep Golf” (Bathykolpos, modern Büyük Dere), one goes alongside the altar of the Megarian hero Saro,⁷³ the Simaeum promontory (modern Mazar burnu), Scletrina golf (modern Kalafat Yeri) and the altars of Apollo and the Mother of the Gods, where Medea planted a laurel.⁷⁴ Therefore, only the Miltum Promontorium (modern Telli tabya köyü) separate the traveller from the European Hieron, with the temples of Serapis and of the Phrygian Goddess.⁷⁵ Further on to the Black Sea, there are Timea,⁷⁶ Chrysorrhoa⁷⁷ and the foundations of the Ephesians, Lycians and Myrleans⁷⁸ as well as another temple of Aphrodite and, maybe of Artemis (which would explain the toponym 'Phosphoros'). This is Phineus’ shore⁷⁹ with the City of the Vultures (Gypopolis/Phinopolis),⁸⁰ and, as one turns to the left following the European shore, the Cyaneas Rocks in front of the Panium/ Φανάριον promontory (modern Rumeli Feneri).⁸¹

2c. Economy

As all the modern historians of Byzantion have remarked,⁸² the city took financial advantage of his geographical position of crossing point between the Black Sea and the Aegean. But the ancient authors, in Greek and Roman times, were particularly impressed by the reputation of the Byzantines fisheries:⁸³ from Archestratos’ oysters, parrot wrasses, tuna in Aristotle’s Politeia, Polybius’ historical analysis and Philostratus’ the Elder topographical image of Bosporus,⁸⁴ the richness and the variety of the fish exported all around the Mediterranean are the constant supply of this city.

2d. Mythology and Religion

The Argonautic stations of the Bosporus are often duplicated, as a result of the competition between the two Megarian foundations situated on the opposite shores of the strait. So, Strabo has counted⁸⁵ two series of Cyaneae (maybe the modern Eşek Adası in Asia and the Öreke taşı in Europe, see supra), situated at equal distances from two sacred (Hiera) promontories (the modern Rumeli and Anatoli Kavağı): the European one, with the temples of Serapis and Hermes (?), belonging to Byzantium and a second one, the Asiatic, with a sanctuary of the Twelve Gods, of Zeus Ourios and maybe of Artemisand Poseidon,⁸⁶ taken by the Byzantines from the Calchedonians. These points have always been essential landmarks for the navigators to and from the Euxine; thus, they have been integrated into all the episodes of the Argonautic maritime cycle: it is Phrixos, son of Athamas and brother of Helle, who left Orchomenos for Colchis and set up the first sanctuary of the Twelve Gods; probably a second Bosporan port, situated on the Asiatic shore, kept his name (Phrixou limen). In their way back to Greece, his sons have probably sacrificed to the Twelve Gods in this same sanctuary, whose foundation was attributed by some mythographers to themselves.⁸⁷ Finally, Apollonius of Rhodes has chosen the most famous version and considered Jason to be the founder of the Asiatic Hieron.⁸⁸ Before the arrival of the Argonauts, the shores were inhabited by barbarians, dominated by the Asiatic Amykos and the European Phineus: in such a hostile maritime and terrestrial environment, only the mystical help of an Old man of the sea could save the navigators. Finally, Jason was not the only one to have his Jasonion close to Byzantium. The return of the Argonauts through the Thracian Bosporus explained the toponyms related to Medea: at the Pontic extremity of the Asiatic shore there was a Tower of Medea, close to the Ancyraion where Jason left its anchor; on the European shore, Dionysius of Byzantium related the Colchian magician to Pharmacia; she planted a laurel close to the European sanctuary of the Mother of the Gods and married Jason at Byzantium. This is just another remarkable example for the ancient Byzantine propaganda that has constantly tried to integrate the city into one of the most important Panhellenic myths.