When Muhammad was forty years old there came to him a Divine Call, bidding him teach his people to abandon their idols, to worship God, and to accept him as God’s Prophet. At first Muhammad met with the most bitter opposition, and in the year 622 A.D. he had to flee from Mecca to a city called Yathreb, which received him and made him its chief magistrate. Ever since that event this city has been called Medinat-un-Nabi, the City of the Prophet; or, shortly, Medina. The flight of Muhammad from Mecca is called the Hegira, and it is from this event that the Muhammadan calendar dates. In the year 630 A.D. Mecca was conquered, and shortly after this all Arabia submitted to the claims of the prophet. After Muhammad’s death the Arabs set forth to conquer the world and to convert it to Islam. They subdued Egypt and Syria and the plain of the Euphrates. They marched to the gates of Constantinople, and through Northern Africa to the Strait of Gibraltar, and beyond Gibraltar through Spain into France, there to suffer a great defeat at the hands of the Christian Franks, which saved the remainder of Christendom. All this was accomplished in little more than a hundred years from the Hegira. But the Musulmans did not wage war only against Christendom. Their armies advanced from the Euphrates up on to the Persian plateau and down into the lowlands of Turkestan in the heart of Asia, and over the Hindu Kush into Afghanistan, and then down into the plain of the River Indus. Already in the seventh century there had been Musulman incursions into India overseas, by way of Sind. In the eleventh century after Christ the Musulmans entered Gangetic India, and took Delhi. They founded there a Muhammadan realm, which presently extended through most of Northern India. [Sidenote: 3. The Mogul Empire at its greatest extent.] Five hundred years later a second Musulman invasion, more effective than the first, came into India by way of Delhi. The Moguls or Mongols of Central Asia had been converted to Islam, and in the time of our King Henry the Eighth they refounded the Musulman power at Delhi. For a hundred and fifty years, from the time of our Queen Elizabeth to that of our Queen Anne, the series of Mogul Emperors, from Humayun to Aurangzeb, ruled in splendid state practically the whole of India. This map shows the greatest spread of the Mogul Empire. Agra, a hundred miles down the Jumna from Delhi, became a subsidiary capital to Delhi, and in these two cities we have to-day the supreme examples of Muhammadan architectural art.