Proto-Tocharian is the unattested reconstructed ancestor of an Indo-European eponymous extinct branch, known from manuscripts dating from the 5th to the 8th century AD, which were on the northern edge of the Tarim Basin and the Lop Desert.
A body of loanwords and names found in Prakrit documents from the Lop Nor basin have been dubbed Tocharian C (Kroränian).
The basic problems are: Historically, the evolution of the Tocharian vowels was the last part of the diachronic phonology to be understood.
"[4] However, rapid progress towards understanding the evolution of the vocalic system, and with it the phonology as a whole, occurred during the period of approximately 1948–1960, beginning with Sieg and Siegling (1949).
[5] By 1960, the system was well-enough understood that Krause and Thomas's seminal work of that year[6] is still considered one of the most important Tocharian grammatical handbooks.
Other than palatalization effects, both vowels are reflected identically in both Tocharian A and B, and hence a number of researchers project the merger back to Proto-Tocharian.
However, some umlaut processes are thought to have operated differently on the two vowels, and as a result Ringe (as well as Adams[10] and some other scholars) prefer to distinguish the two in Proto-Tocharian.
This vowel does trigger palatalization, and is thought by Ringe to stem primarily from PIE *oy and from loanwords.
Sanskrit pū́rva-) > PToch *pä́rwë > TB parwe, TA pärwa-t Notes: Proto-Tocharian had phonemic stress, although its position varies depending on the researcher.
Ringe,[9] however, prefers to project the PIE stress unchanged into Proto-Tocharian, and assumes that the radically different system seen in Tocharian B evolved within the separate history of that language.
It is generally agreed that *ih₂ became Proto-Tocharian *yā; a similar change occurred in Ancient Greek.
As elsewhere, the main difficulty is that, relative to other Indo-European languages, Tocharian is sparsely attested and was subject to a particularly large number of analogical changes.
When this produces impossible consonant sequences, these are rectified by vocalizing w and y into u and i, if possible; otherwise, an epenthetic ä is inserted.
Note that most consonant sequences are tolerated word-initially, including unexpected cases like rt-, ys- and lks-.
Many occurrences of c and ts can be explained by the differing effects of a following y vs. a front vowel (see above), but a number of difficult cases remain.
This in turn suggests that some sound changes must have operated on particular dentals, but not others, prior to the general loss of contrastive voicing and aspiration.
Ringe suggests the following changes, in approximate order:[9] Even with this explanation, a lot of words don't have the expected outcomes and require appeal to analogy.
Ringe needs to appeal to an analogical depalatalization, based on other forms of the verb with different ablaut patterns in which palatalization was not triggered.
Centum languages are mostly found in western and southern Europe (Greek, Italic, Celtic, Germanic).
In that sense, Proto-Tocharian (to some extent like the Greek and the Anatolian languages) seems to have been an isolate in the "satem" (i.e. palatovelar to sibilant) phonetic regions of Indo-European-speaking populations.
For instance, the Tocharian B word yakwe, the Tocharian A word yuk < Proto-Tocharian *yä́kwë < PIE *h₁éḱwos, all meaning "horse", are declined as follows:[8] When referring to humans, the oblique singular of most adjectives and of some nouns is marked in both varieties by an ending -(a)ṃ, which also appears in the secondary cases.
This is thought to stem from the generalization of n-stem adjectives as an indication of determinative semantics, seen most prominently in the weak adjective declension in the Germanic languages (where it cooccurs with definite articles and determiners), but also in Latin and Greek n-stem nouns (especially proper names) formed from adjectives, e.g. Latin Catō (genitive Catōnis) literally "the sly one" [citation needed] < catus "sly", Greek Plátōn literally "the broad-shouldered one" < platús "broad".
[16] The majority of Proto-Indo-European verbal classes and categories are represented in some manner in Tocharian, although not necessarily with the same function.
As in Sanskrit, Ancient Greek and (to a lesser extent) Latin, there are independent sets of classes in the indicative present, subjunctive, perfect, imperative, and to a limited extent optative and imperfect, and there is no general correspondence among the different sets of classes, meaning that each verb must be specified using a number of principal parts.