For two days they travelled over high, rocky mountains, by the worst roads they found in Yemen. The country was poor and thinly inhabited, and the declivities only began to be clothed with trees and terraced into coffee plantations as they approached the plains. The poorer regions are not considered entirely safe by the Arabs, as the people frequently plunder defenceless travellers; but the party passed safely through this region, and reached Beit el-Fakih after a week’s journey from Sana. Niebuhr and his companions reached Mocha early in August, and toward the end of that month sailed in an English vessel for Bombay, after a stay of ten months in Yemen. The artist of the expedition and the Swedish servant died on the Indian Ocean, and the physician in India, a few months afterward, leaving Niebuhr the sole survivor of the six persons who left Copenhagen three years before. After having sent home the journals and collections of the expedition he continued his travels through the Persian Gulf, Bagdad, Armenia, and Asia Minor, finally reaching Denmark in 1767. The era of intelligent, scientific exploration, which is now rapidly opening all parts of the world to our knowledge, may be said to have been inaugurated by his travels. CHAPTER IV. BURCKHARDT’S JOURNEY TO MECCA AND MEDINA. BURCKHARDT, to whom we are indebted for the first careful and complete description of the holy cities of Arabia, was a native of Lausanne, in Switzerland. After having been educated in Germany, he went to London with the intention of entering the English military service, but was persuaded by Sir Joseph Banks to apply to the African Association for an appointment to explore the Sahara, and the then unknown negro kingdoms of Central Africa. His offer was accepted, and after some preparation he went to Aleppo, in Syria, where he remained for a year or two, engaged in studying Arabic and familiarizing himself with Oriental habits of life. His first journeys in Syria and Palestine, which were only meant as preparations for the African exploration, led to the most important results. He was the first to visit the country of Hauran—the Bashan of Scripture—lying southeast of Damascus. After this he passed through Moab, east of the Dead Sea, and under the pretence of making a pilgrimage to the tomb of Aaron on Mount Hor, discovered the rock-hewn palaces and temples of Petra, which had been for many centuries lost to the world.