Just at the same time as the Arabs, in the first flush of victory, poured into Egypt, a small force crossed the Arabian Sea and entered Baluchistan, and a century later the whole of Sind passed into Arab hands. Another two centuries and the Mahomedan flood was pouring irresistibly into India, no longer across the Arabian Sea, but from Central Asia through the great northern passes, until in successive waves it submerged for a time almost the whole of India. Now if we look back upon the fifteen centuries of Indian history, of which I have sought to reconstitute the chief landmarks before the Mahomedan invasions, the two salient features that emerge from the twilight are the failure of the Aryan Hindus to achieve any permanent form of political unity or stability, and their success, on the other hand, in building up on adamantine foundations a complex but vital social system. The supple and subtle forces of Hinduism had already in prehistoric times welded together the discordant beliefs and customs of a vast variety of races into a comprehensive fabric sufficiently elastic to shelter most of the indigenous populations of India, and sufficiently rigid to secure the Aryan Hindu ascendancy. Of its marvellous tenacity and powers of resorption there can be no greater proof than the elimination of Buddhism from India, where, in spite of its tremendous uplift in the days of Asoka and the intermittent favours it enjoyed under later and lesser monarchs, it was already moribund before the Mahomedans gave it its final deathblow. Jainism, contemporary and closely akin to Buddhism, never rose to the same pre-eminence, and perhaps for that very reason secured a longer though more obscure lease of life, and still survives as a respectable but numerically quite unimportant sect. But indomitably powerful as a social amalgam, Hinduism failed to generate any politically constructive force that could endure much beyond the lifetime of some exceptionally gifted conqueror. The Mauryan and the Gupta dynasties succumbed as irretrievably to the centrifugal forces of petty states and clans perpetually striving for mastery as the more ephemeral kingdoms of Kanishka and Harsha. They all in turn crumbled away, and, in a land of many races and languages and climates, split up into many states and groups of states constantly at strife and constantly changing masters and frontiers. Hinduism alone always survived with its crowded and ever-expanding pantheon of gods and goddesses for the multitude, with its subtle and elastic philosophies for the elect, with the doctrine of infinite reincarnations for all, and, bound up with it, the iron law of caste.