The Taurus system is another such chain trending westward, dividing Asia Minor from the rest of Asia, skirting the southern coast-line, then breaking and scattering as the level falls towards the west until it descends below the sea, where its hilltops, still projecting, form the Ægean archipelago, until drawn together it rises to dry land on the soil of Greece. In the heart of these mountains, the two main sources of the river Euphrates flow in a westerly direction until they unite above Malatia;[4] thence twisting and turning ever, in its search for a passage through the rocky ramparts that oppose it, the great river makes an easterly contour until nearing the plains. Before reaching Gerger, however, its direction is changed once more, turning westward in a long curve past Samsat towards Aintab, and southward to the latitude of Aleppo: from here its course becomes more tranquil and direct towards the Persian Gulf. The bend of the Euphrates below Malatia marks for the present the boundary of the Hittite country on the east. The whole mountainous region lying to the west of this landmark is divided by the gorges of the Pyramus, comprising the bleak easterly heights of the main Taurus range on the one hand, and the more broken but less barren regions of the Anti-Taurus which lie within. From the Taurus numerous torrents fall southward to join the bend of the Euphrates, while the northern slopes of the same range look down on the deep valley of the Tochma Su. This river, flowing eastward, is another main tributary of the Euphrates, which it joins not far from Malatia, and it forms our present boundary to the north in that direction.[5] Its sources are found high up past Gurun in the main watershed, from which some rivers flow southward to the Cilician plain, others north-west to feed the Halys. [Illustration: PLATE II A VALLEY IN THE TAURUS (_See p. 5._) HEAD-WATERS OF THE HALYS NEAR SIVAS (_See p. 26._)]