It would be difficult to exaggerate the importance to India of the existence of the great Indian Desert of Rajputana. The ocean to the southeast and the southwest of the Peninsula was an ample protection against overseas invasion until the Europeans rounded the Cape of Good Hope. The vast length of the Himalaya, backed by the desert plateau of Tibet, was an equal defence on a third side. Only to the northwest does India lie relatively open to the incursions of the warlike peoples of Western and Central Asia. It is precisely in that direction, as a great barrier extending northeastward from the Rann of Cutch, that we find the Indian Desert, and in rear of the Desert the minor bulwark constituted by the Aravalli range. Only between the northeastern extremity of the desert and the foot of the Himalayas below Simla is there an easy gateway into India. No river traverses this gateway, which is on the divide between the systems of the Indus and the Jumna-Ganges. Delhi stands on the west bank of the Jumna at the northern extremity of the Aravallis, just where the invading forces from the northwest came through to the navigable waters of the Jumna, which flow southeastward through Hindustan to Bengal. Aided by such powerful natural conditions, the Rajputs have ever been the defenders of India. Unable to prevent the entry of invaders by the direct way to Delhi, they have maintained themselves on the southern flank of the advance, and to-day their princely families proudly trace their lineage back in unbroken descent from ancestors before the Christian era. In the gateway itself, between the desert and the Himalayas, beyond the limits of Rajputana, dwell another people of warlike disposition, the famous Sikhs. Here are still preserved as Feudatory States the Sikh Principalities of Patiala, Nabha, and Jhind.