36. Suppose that Hannibal marched up from Tarascon, going first along the Rhone and then along the Durance from the confluence of the two: he would reach a point just opposite Cavaillon in 30 Roman miles. The obvious route from Tarascon to Cavaillon is straight across country, on the line of the Roman road; and in saying so emphatically that Hannibal marched along the river (_para ton potamon_, iii. 47. 1) or close along the river (_par’ auton ton potamon_, iii. 39. 9) Polybios may be saying it to negative the notion of his marching straight across. Strabo mentions (iv. 1. 3) that Cavaillon was on the Roman road from Tarascon to the Alps; and as it was on the north bank of the Durance, people coming from Tarascon must have crossed. He elsewhere (iv. 1. 11) mentions the ferry (_porthmeion_) at Cavaillon in speaking of people going from Marseilles to places between the north bank of the Durance and the Rhone. The ferry would not have been established there unless that was the most convenient place for crossing; and when Polybios says that Hannibal reached the Island, he presumably is speaking of the usual point for crossing to it, not the point whence it could first be seen. In fact, whilst Scipio was looking for Hannibal at the crossing of the Rhone, Hannibal had reached the crossing of the Durance and could retire further north if Scipio came on. Scipio, however, went back. 37. Livy’s version (xxi. 31) is that the civil-war in the Island was between two factions of the Allobriges who lived near there; and that after finishing off their war, Hannibal did not take the direct route to the Alps, but turned to the left into the territory of the Tricastini, skirted the territory of the Vocontii, entered the territory of the Tricorii, and met no check until he reached the Durance, but had serious difficulties there. Polybios, however, says nothing of any difficulties at the Durance, nor does he mention any of these tribes except the Allobriges; and he does not mention this tribe here, but only at a later stage of Hannibal’s march. He says (iii. 49. 13) that the successful faction in the Island sent a force with Hannibal to act as rear-guard and keep off attacks by the Allobriges; but if both the factions had been Allobriges, as Livy says, Polybios would have spoken of attacks by the defeated faction only, not attacks by the Allobriges. 38. Strabo says (iv. 1. 11) that in his time, which also was Livy’s time, the Allobriges were merely husbandmen, though in former ages they had armies of tens of thousands in the field. He mentions Vienne, on the Rhone, as their chief town; but Dion Cassius (xlvi. 50) shows clearly that they did not take Vienne till a century and a half after Hannibal’s time--the city of Lyons was founded in 43 B.C. to house the inhabitants of Vienne after the Allobriges had driven them out. And other tribes may likewise have shifted their position between Hannibal’s time and the time of Polybios or Ptolemy or Strabo.