The great peninsula of Arabia was in the earliest times inhabited by a population of the Semitic stock, in all essential respects similar to that which inhabits it now, partly concentrated in cities, partly wandering in tribes through the extensive deserts which mark the surface of the country. The inhabitants of the towns subsist by agriculture and commerce; the wandering tribes by cattle rearing and pillage. In ancient times, as now, the Arabs were celebrated for their expert horsemanship, their hospitality, their eloquence, and their free indomitable spirit. In religion, however, the modern Arabs, who are Mohammedans, differ from the ancient Arabs, who were idolaters, chiefly worshippers of the celestial luminaries, nowhere so beautiful as in the sky of an Arabian desert. The Arabs themselves trace their history back, the older tribes to Kahtan (the Joktan of the 10th chapter of Genesis), the latter to Adnan, a descendant of Ishmael, the offspring of Abraham. It is unnecessary, however, to enter into this history, as Arabia was not incorporated with the Persian empire, and only assumed historical importance in later times, when it sent forth the religion of Mohammed over the East.