The oldest city within modern France, Marseille, was founded around 600 BC by Greeks from the Asia Minor city of Phocaea (as mentioned by Thucydides Bk1,13, Strabo, Athenaeus and Justin) as a trading post or emporion under the name Μασσαλία (Massalia).
A foundation myth reported by Aristotle in the 4th century BC as well as by Latin authors, recounts how the Phocaean Protis (son of Euxenus) married Gyptis (or Petta), the daughter of a local Segobriges king called Nannus, thus giving him the right to receive a piece of land where he was able to found a city. The contours of the Greek city have been partially excavated in several neighborhoods. The Phocaean Greeks introduced the cult of Artemis, as in their other colonies.
It is thought that contacts started even earlier however, as Ionian Greeks traded in the Western Mediterranean and Spain, but only very little remains from that earlier period. Contacts developed undisputedly from 600 BC, between the Celts and Celto-Ligurans and the Greeks in the city of Marseille and their other colonies such as Agde, Nice, Antibes, Monaco, Emporiae and Rhoda. The Greeks from Phocaea also founded settlements in the island of Corsica, such as at Alalia. From Massalia, the Phocaean Greeks also founded cities in northeastern Spain such as Emporiae and Rhoda.
Before the Greeks came to pre-eminence in the Gulf of Lion, trade was mainly handled by Etruscans and Carthaginians. The Greeks of Massalia had recurrent conflicts with Gauls and Ligurians of the region, and engaged in naval battles against Carthaginians in the late 6th century (Thucydides 1.13) and probably in 490 BC, and soon entered into a treaty with Rome.
According to Charles Ebel, writing in the 1960s, "Massalia was not an isolated Greek city, but had developed an Empire of its own along the coast of southern Gaul by the fourth century". But the idea of a Massalian "empire" is no longer credible in the light of recent archaeological evidence, which shows that Massalia never even had a very large chora (agricultural territory under its direct control). However further archaeological evidence since shows Massalia had over twelve cities in its network in France, Spain, Monaco and Corsica. Cities Massalia founded that still exist today are Nice, Antibes, Monaco, Le Brusc, Agde, and Aleria. There is evidence of direct rule of at least two of their cities with a flexible system of autonomy as suggested by Emporion and Rhodus' own coin minting. Massalia's empire was not the same as the monolithic of the ancient world or of the nineteenth century being a scattered group of cities connected by the sea and rivers. The Delian League was also a scattered group of cities spread far across the sea and became known as the Athenian Empire.
Greek Marseille eventually became a centre of culture which drew some Roman parents to send their children there to be educated. According to earlier views, a purported hellenization of Southern France prior to the Roman Conquest of Transalpine Gaul is thought to have been largely due to the influence of Massalia. However, more recent scholarship has shown that the idea of Hellenization was illusory (and that the concept itself is seriously flawed). The power and cultural influence of Massalia have been called into question by demonstrating the limited territorial control of the city and showing the distinctive cultures of indigenous societies. Local Gauls were not Grecophiles who wanted to imitate Greek culture, but peoples who selectively consumed a very limited range of Greek objects (mostly wine and drinking ceramics) that they incorporated into their own cultural practices according to their own systems of value.
These eastern Greeks, established on the shores of southern France, were in close relations with the Celtic inhabitants of the region, and during the late 6th and 5th centuries BC Greek artifacts penetrated northwards alongs the Rhône and Saône valleys as well as the Isère. Massalian grey monochrome pottery has been discovered in the Hautes Alpes and as far north as Lons-le-Saunier, as well as three-winged bronze arrowheads as far as northern France, and amphorae from Marseille and Attic pottery at Mont Lassois. The site of Vix in northern Burgundy is a well-known example of a Hallstatt settlement where such Mediterranean objects were consumed, albeit in small quantities. Some, like the famous Vix krater, were spectacular in nature.
From Marseille, maritime trade also developed with Languedoc and Etruria, and with the Greek city of Emporiae on the coast of Spain. Massalia traded as least as far as Gades and Tartessus on the western coast of the Iberian peninsula, as described in the Massaliote Periplus, although this trade was probably blocked by the Carthaginians at the Pillars of Hercules after 500 BC.
The mother city of Phocaea would ultimately be destroyed by the Persians in 545, further reinforcing the exodus of the Phocaeans to their settlements of the Western Mediterranean. Trading links were extensive, in iron, spices, wheat and slaves. It has been claimed frequently that a trade in tin, indispensable for the manufacture of bronze, seems to have been established at that time between Cornwall in modern England, through the Channel, and along the Seine valley, Burgundy and the Rhône-Saône valleys to Marseille. However, the evidence for this is weak, at best.
Overland trade with Celtic countries beyond the Mediterranean region declined around 500 BC, in conjunction with the troubles following the end of the Halstatt civilization. The site of Mont Lassois was abandoned around that time.
The Greek colony of Massalia remained active in the following centuries. Around 325 BC, Pytheas (Ancient Greek Πυθέας ὁ Μασσαλιώτης) made a voyage of exploration to northwestern Europe as far as the Arctic Circle from his city of Marseilles. His discoveries contributed to the elaboration of the ancient world maps of Dicaearchus, Timaeus and Eratosthenes, and to the development of the parallels of latitude.
The La Tène style, based on floral ornamentation, in contrast to the geometric styles of Early Iron Age Europe, can be traced to an imaginative re-interpretation of motifs on imported objects of Greek or Etruscan origin.
During his conquest of Gaul, Caesar reported that the Helvetii were in possession of documents in the Greek script, and all Gaulish coins used the Greek script until about 50 BC.
Celtic coinage emerged in the 4th century BC, and, influenced by trade with the Greeks and the supply of mercenaries to them, initially copied Greek designs. Celtic coinage was influenced by Greek designs, and Greek letters can be found on various Celtic coins, especially those of Southern France. Greek coinage occurred in the three Greek cities of Massalia, Emporiae and Rhoda, and was copied throughout southern Gaul.
Coins in northern Gaul were especially influenced by the coinage of Philip II of Macedon and his famous son Alexander the Great.
Celtic coins often retained Greek subjects, such as the head of Apollo on the obverse and two-horse chariot on the reverse of the gold stater of Philip II, but developed their own style from that basis, thus establishing a Graeco-Celtic synthesis.
After this first period in which Celtic coins rather faithfully reproduced Greek types, designs started to become more symbolic, as exemplified by the coinage of the Parisii in the Belgic region of northern France. By the 2nd century BC, the Greek chariot was only represented by a symbolic wheel.
The Armorican Celtic style in northwestern Gaul also developed from Celtic designs from the Rhine valley, themselves derived from earlier Greek prototypes such as the wine scroll and split palmette.
With the Roman invasion of Gaul, Greek-inspired Celtic coinage started to incorporate Roman influence instead, until it disappeared to be completely replaced by Roman coinage.
By the 1st century BC, the coinage of the Greeks of Marseille circulated freely in Gaul, also influencing coinage as far afield as Great Britain. The coins of the Sunbury hoard, thought to have been manufactured in Kent, show designs derived from Greek coins from Marseille with the stylised head of Apollo and a butting bull. Recently original bronze coins 3rd-2nd century BC from Greek Marseille have been found in several locations around Kent, UK.
Celtic coin designs progressively became more abstract, as is exemplified by the coins of the Parisii: