As a general rule the mighty chain of the Himalaya has effectually separated the peoples living north and south of it, and the instances in history are rare of any collision between them. Of all such collisions the most important was that which has now to be described as the main cause of the tightening of the hold of China upon Tibet. The mountain kingdom of Nepaul was equally independent of the British and the Mogul Empire of Delhi. It was ruled by three separate kings, until in the year 1769 the Goorkha chief Prithi Narayan established the supremacy of that warlike race. The Goorkhas cared nothing for trade, and their exactions resulted in the cessation of the commercial intercourse which had existed under the Nepaulese kings between India and Tibet. Their martial instincts led them to carry on raids into both Tibet and India. The Tibetans were unequal to the task of punishing or restraining them, and at last the Goorkhas were inspired with such confidence that they undertook the invasion of their country. It is said that the Goorkhas were encouraged to take this, step by the belief that the Chinese would not interfere, and that the lamaseries contained an incalculable amount of treasure. The Goorkhas invaded Tibet in 1791 with an army of less than 20,000 men, and, advancing through the Kirong and Kuti passes, overcame the frontier guards, and carried all before them up to the town of Degarehi, where they plundered the famous lamasery of Teshu Lumbo, the residence of the Teshu Lama. Having achieved this success and gratified their desire for plunder, the Goorkhas remained inactive for some weeks, and wasted much precious time. The Tibetans did not attempt a resistance, which their want of military skill and their natural cowardice would have rendered futile, but they sent express messengers to Pekin entreating the Chinese emperor to send an army to their assistance. Keen Lung had not sent troops to put a stop to the raids committed on the frontier by the Goorkhas; but when he heard that a portion of his dominions was invaded, and that the predominance of his country in the holy land of Buddhism was in danger, he at once ordered his generals to collect all the forces they could and to march without delay to expel the foreign invader. He may have been urged to increased activity by the knowledge that the Tibetans had also appealed for aid to the British, and by his being ignorant what steps the Indian Government would take. Within a very short time of the receipt of the appeal for assistance a Chinese army of 70,000 men was dispatched into Tibet, and the Goorkhas, awed by this much larger force, began their retreat to their own country. Their march was delayed by the magnitude of their spoil, and before they had reached the passes through the Himalaya the Chinese army had caught them up. In the hope of securing a safe retreat for his baggage and booty, the Goorkha commander drew up his force in battle array on the