The remarkable divergences and alterations which a very slight difference in locality causes to exist in the tongues of the Tibeto-Burman hill-tribes have been frequently adverted to, and are, in fact, one of the stock examples of the birth and growth of dialectic change in language. In truth, it must be admitted that in no part of the world are the conditions more favourable to such growth than in the mass of mountains which extends from the Himalayas to Cape Negrais, and which forms the habitat of many of the most interesting of these tribes. Favoured by an abnormally heavy rainfall, the dense jungles which everywhere cover these hills would successfully defy the efforts of even civilized people for their destruction. As it is, except for temporary clearings for cultivation, and somewhat more permanent ones immediately round the villages, these forests remain practically intact, forming, together with the extraordinarily broken character of the ground, one of the most powerful obstacles conceivable to intercourse between the various villages. Such intercourse, therefore, except when it partakes of a raid or foray, is usually on a very limited scale; nor, as a matter of fact, was anything more extended desired by the villagers until quite recently. As McCabe says of the Nagas: “They have remained isolated on their hill-tops, only deigning to visit their immediate neighbours when a longing for their heads has become too strong to be resisted.”