Notwithstanding the numerous books that have been published on Tibet, from the time of Bogle and Manning, a century back, down to the more recent descriptions of the country by Rockhill, Bower, and others, the public generally have but a hazy idea of the wide Tibetan region, or of its great value to us and to all Europeans whose lot is cast in the surrounding lands, dominated by the huge table-land that towers above them. Tibet is the heart of Asia, rightly called the roof of the world; it forms the nucleus of the great Asiatic continent, and from it may be said to depend the low-lying peripheral countries by which it is surrounded, India, Burma, Siam, and Cochin-China on the south; China proper on the west; and the Tarim Basin with East Turkestan on the north. The great rivers which water these countries have all their sources in the high plateau,—the Indus, the Ganges, and the Brahmaputra, which flow through India and debouch into the Indian Ocean on the South; the Irrawaddy and the Salwin in Burma flowing into the Bay of Bengal; the Lan-tsan-kiang, or Mekong, which crosses Upper Siam and Cochin-China and, taking a south-west course, flows into the China Sea near Saigon; and finally the Red River of Tongking, which rises in the Chinese province of Yunnan, itself a high table-land and peninsular extension of the Tibetan plateau.