Between the islands of the Malay archipelago from Sumatra to New Guinea, and the neighbouring Asiatic continent, no definite relations appear ever to have existed, and no distinctly marked boundary for Asia has been established by the old geographers in this quarter.
It was of little importance, and is only mentioned by geographers and in inscriptions.
Wagner's year-book, Geographische Jahrbuch, published at Gotha, is the best systematic record of the progress of geography in all departments; and Haack's Geografihen Kalender, also published annually at Gotha, gives complete lists of the geographical societies and geographers of the world.
In the restoration of the outlines of ancient and medieval geography in Asia Sven Hedin's discoveries of the actual remains of cities which have long been buried under the advancing waves of sand in the Takla Makan desert, cities which flourished in the comparatively recent period of Buddhist ascendancy in High Asia, is of the very highest interest, filling up a blank in the identification of sites mentioned by early geographers and illustrating more fully the course of old pilgrim routes.
This depression is supposed to be a relic of the former post-Pliocene connexion between the Black Sea and the Caspian, and is accepted by most geographers as the natural frontier between Europe and Asia, while others make the dividing-line coincide with the principal water-parting of the Caucasus mountain system.