Whereas Euboean pottery-most of it Eretrian-is found more or less throughout the Mediterranean basin during the second half of the 8th century, ca. 700 BC it suddenly ceases to be exported. From that date onward, it appears in significant quantities only on Delos, an important religious center at the heart of the Cyclades. Attempts have been made to establish a relationship between this phenomenon and the Lelantine War: Eretria is supposed to have been defeated by Chalkis and its allies and forced to withdraw from the international scene. It has even been suggested that the city was destroyed and temporarily abandoned at the beginning of the 7th century. But archaeological remains and the few extant literary sources suggest a very different picture. There is no doubt that Eretria continued to develop throughout the Archaic Period.
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The 7th century
Even though literary sources are lacking, a number of archaeological remains indicate that Eretria was prosperous and dynamic in the 7th century. Suffice it to note the construction, at ca. 680 BC, of a massive wall diverting the course of the river, which had formerly run along the west side of the city and whose torrential crests periodically flooded the city's dwellings. At the same time, a first "hundred foot temple" (hekatompedon) was erected in the future Sanctuary of Apollo Daphnephoros.
The 6th century
In the second half of the 6th century, Eretria entered a particularly dynamic phase of its history. First, ca. 550, it surrounded itself with a city wall. Ca. 540, the city welcomed the exiled Pisitratos, tyrant of Athens, and his sons, who raised funds and hired mercenaries from all over Greece to regain power. They were supported by several allies, including the Thebans and the powerful ruler Lygdamis of Naxos. Pisistratos and his allies embarked from Eretria when they re-conquered power in Attica (Herodotos, I 61-62). The Temple of Apollo, built ca. 530 BC, pays a clear ackowledgement to Athens: the sculptures of the west pediment, completed ca. 510 BC, represent Theseus in his fight against the Amazons, a theme particularly dear to the Athenians whose influence is further emphasized by the central position occupied by Athena, tutelary deity of Athens.
A few years later, in 499, an Eretrian squadron of ten ships rushed with the Athenian fleet to the rescue of the Milesians and other Ionian Greeks who had revolted against Persian domination. The Eretrians ended up paying a high price for this support: in 490, Persian troops besieged and stormed the city before landing at Marathon. Diodoros of Sicily mentions Eretria in his thalassocracy list for a period of 15 years (VII 11, 1). We can situate these years of Eretrian naval supremacy in the period starting in 506, year of a memorable defeat of Chalkis by the Athenians, and ending in 490.