Thapsacus

thumb | right | Map of area Thapsacus (; Tipsah) was an ancient town along the western bank of the Euphrates river that would now lie in modern Syria. Thapsacus was the Greek and Roman name for the town. The town was important and prosperous due to its river crossing, which allowed east-west land traffic to pass through it. Its precise location is unknown and there are several different locations identified as the site of Thapsacus. One possibility is a location close to Carchemish, which now lies in Turkey, on its border with Syria. Karkamış and Jarabulus are the closest modern towns in Turkey and Syria respectively. More recently it has been suggested that Thapsacus was renamed to Seleucia at the Zeugma, which lies further upstream on the Euphrates, or that it is identical with the Jebel Khalid, which lies a bit farther downstream on the river.

==Location== === Possible identification with Carchemish === Farrell and Engels argue that Thapsacus was located in the vicinity of Carchemish. There are several classical sources which support this. The oldest source is the 401 BC marching itinerary of Cyrus the Younger as given by Xenophon, in his Anabasis. Farrell calculates that the march rates support a crossing at Carchemish, then across to the Balikh River and then down that river to its junction with the Euphrates. The Greek geographer Eratosthenes, who lived during the third and second century BC, gave a distance of 4,800 stades from Thapsacus to Babylon through the route along the Euphrates. This distance is , which conforms to the actual distance of about between Carchemish and Babylon. Eratosthenes also gives a distance of 2,400 stades for the shortest route to the Tigris from Thapsacus. This distance is , which is also the approximate distance as measured with modern techniques. Arrian writes that Alexander the Great kept the Euphrates and the Armenian mountains on his left after he crossed the Euphrates at Thapsacus in 331 BC. Engels interprets this as additional support for a location near Carchemish.