We must now turn to an event of great historical importance although its details are not relevant to the subject of this book, namely the Mohammedan conquest. Three periods in it may be recognized. First, the conquest of Sind in 712 A.D. by the Arabs, who held it till the eleventh century but without disturbing or influencing India beyond their immediate neighbourhood. Secondly, the period of invasions and dynasties which are commonly called Turki (c. 1000-1526 A.D.). The progress of Islam in Central Asia coincided with the advance to the west and south of vigorous tribes known as Turks or Mongols, and by giving them a religious and legal discipline admirably suited to their stage of civilization, it greatly increased their political efficiency. The Moslim invaders of India started from principalities founded by these tribes near the north-western frontier with a military population of mixed blood and a veneer of Perso-Arabic civilization, and apart from the greater invasions, there were incursions and settlements of Turkis, Afghans and Mongols. The whole period was troublous and distracted. The third period was more significant and relatively stable. Baber, a Turkish prince of Fergana, captured Delhi in 1526 and founded the power of the Mughals, which during the seventeenth century deserved the name of the Indian Empire. The first serious Moslim incursions were those of Mahmud of Ghazni, who between 997 and 1030 made many raids in which he sacked Kanauj, Muttra, Somnath and many other places but without acquiring them as permanent possessions. Only the Panjab became a Moslim province. In 1150 the rulers of Ghor, a vassal principality near Herat, revolted against Ghazni and occupied its territory, whence the chieftain commonly called Muhammad of Ghor descended on India and subdued Hindustan as well as the Panjab (1175-1206). One of his slaves named Kutb-ud-Din Ibak became his general and viceroy and, when Muhammad died, founded at Delhi the dynasty known as Slave Sultans. They were succeeded by the Khilji Sultans (1290-1318) the most celebrated of whom was the capable but ferocious Ala-ud-Din and these again by the Tughlak dynasty. Muhammad Adil, the second of this line, attempted to move the capital from Delhi to Daulatabad in the Deccan. In 1398 northern India was convulsed by the invasion of Timur who only remained a few months but sacked Delhi with terrible carnage. Many years of confusion followed, and a dynasty known as the Saiyids ruled in greatly diminished territories. But in 1451 arose the Lodi or Afghan dynasty which held the Panjab, Hindustan and Bundelkhand until the advent of the Mughals. These five royal houses do not represent successive invasions from the west. Their founders, though of diverse origin, were all leaders engaged in the troubled politics of northern India, and they all reigned at Delhi, round which a tradition of Empire thus grew up. But the succession was disputed in almost every