It is not a uniform speech, but comprises several dialects which have been classed by Jaeschke into three groups, namely (i) the central or the dialects of Lhasa and the central provinces of U and Tsang (including Spiti) which is the lingua franca of the whole country, (2) the western dialects of Ladak, Lahul, Baltistan and Purig, and (3) the eastern dialects of the province of Khams. In addition to these, however, are many sub-dialects of Tibetan spoken in the frontier Himalayan districts and states outside Tibet, namely, in Kunawar and Bashahr, Garhwal, Kumaon, Nepal including especially the Serpa and Murmi of eastern Nepal, Sikkim (where the dialect is called Danjong-ka), Bhutan (Lho-ka or Duk-ka.), all of which are affiliated to a central group of dialects.
It was at this stage that the language spread in Lahul and Spiti, where the superscribed letters were silent, the d and g finals were hardly heard, and as, os, us were ai, oi, ui.
Spra or spreu (a monkey), now altered into deu at Lhasa, teu in Lahul, Spiti and Tsang, is still more recognizable in the Gyarung shepri and in the following degenerated forms - shreu in Ladak, streu-go in Khams and in cognate languages, soba in Limbu, saheu in Lepcha, simai in Tablung Naga, sibeh in Abor Miri, shibe in Sibsagar Miri, sarrha in Kol, sara in Kuri, &c. Grog-ma (ant), now altered into the spoken t'oma, is still kyoma in Bhutan, and, without the suffix, korok in Gyarung, k'oro- in Sokpa, k'orok, k'alek in Kiranti, &c. Grang-po- (cold), spoken t' ammo, is still grang-mo in Takpa, k'yam in Burmese, &c. A respectful word for " head " is ii, written dbu, which finds its cognates in Murmi thobo, Sibsagar Miri tub, &c. Bya (bird), spoken cha, is still pye in Gyarung.
The greater part of the remainder are found in Bengal on the borders of Burma, on the borders of Nepal, Tibet and Bhutan, and in the Spiti, Lahul and Kanawar districts of the Punjab Himalayas, where many of the inhabitants are of Tibetan origin.
In Ladak the proportion of lamas to the laity is as I to 13, in Spiti I to 7, and in Burmah I to 30" (Lea i.
From the Permian to the Lias the sequence in the central Himalaya shows no sign of a break, nor has any unconformity been proved between the Liassic beds and the overlying Spiti shales, which contain fossils of Middle and Upper Jurassic age.
The Spiti shales are succeeded conformably by Cretaceous beds (Gieumal sandstone below and Chikkim limestone above), and these are followed without a break by Nummulitic beds of Eocene age, much disturbed and altered by intrusions of gabbro and syenite.
Thus, in the Spiti area at least, there appears to have been continuous deposition of marine beds from the Permian Productus shales to the Eocene Nummulitic formation.
From the absence of any well-marked unconformity it is evident that in the northern part of the Himalayan belt, at least in the Spiti area, there can have been no post-Archaean folding of any magnitude until after the deposition of the Nummulitic beds, and that the folding was completed before the later Tertiaries of Hundes were laid down.