LA´SION(Λασίωνor Λασιών), the chief town of the mountainous district of Acroreia in Elis proper, was situated upon the frontiers of Arcadia near Psophis. Curtius places it with great probability in the upper valley of the Ladon, at the Paleokastroof Kúmani, on the road from the Eleian Pylos and Ephyra to Psophis. Lasion was a frequent object of dispute between the Arcadians and Eleians, both of whom laid claim to it. In the war which the Spartans carried on against Elis at the close of the Peloponnesian War, Pausanias, king of Sparta, took Lasion (Diod. 14.17). The invasion of Pausanias is not mentioned by Xenophon in his account of this war; but the latter author relates that, by the treaty of peace concluded between Elis and Sparta in B.C. 400, the Eleians were obliged to give up Lasion, in consequence of its being claimed by the Arcadians. (Xen. Hell. 3.2. 30) In B.C. 366 the Eleians attempted to recover Lasion from the Arcadians; they took the town by surprise, but were shortly afterwards driven out of it again by the Arcadians. (Xen. Hell. 7.4. 13, seq.; Diod. 15.77.) In B.C. 219 Lasion was again a fortress of Elis, but upon the capture of Psophis by Philip, the Eleian garrison at Lasion straightway deserted the place. (Plb. 4.72, 73.) Polybius mentions (5.102) along with Lasion a fortress called Pyrgos, which he places in a district named Perippia. (Leake, Morea, vol. 2. p. 200, seq.; Boblaye, Récherches, &c. p. 125; Curtius, Peloponnesos, vol. 1. p. 41.)