Proto-Tocharian, also spelled Proto-Tokharian ( or ), is the reconstructed proto-language of the extinct Tocharian branch of the Indo-European languages.
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. The discovery of this language family in the early 20th century contradicted the formerly prevalent idea of an east–west division of the Indo-European language family on the centum–satem isogloss, and prompted reinvigorated study of the family.
The documents record two closely related languages, called Tocharian A (also East Tocharian, Agnean or Turfanian) and Tocharian B (West Tocharian or Kuchean). The subject matter of the texts suggests that Tocharian A was more archaic and used as a Buddhist liturgical language, while Tocharian B was more actively spoken in the entire area from Turfan in the east to Tumshuq in the west. A body of loanwords and names found in Prakrit documents from the Lop Nor basin have been dubbed Tocharian C (Kroränian). A claimed find of ten Tocharian C texts written in Kharoṣṭhī script has been discredited.
Tocharian A and Tocharian B, the two major languages descendant of Proto-Tocharian, are mutually unintelligible, which led linguists to think that the split of Proto-Tocharian in several branches was several centuries prior. As part of the same language family, the Tocharian languages and their common ancestor are studied together by scholars.
Evolution
Sound changes
Proto-Tocharian underwent extensive phonological changes from Proto-Indo-European, including major vowel developments, consonant simplification, and widespread palatalization.
Laryngeal coloring: PIE laryngeals affected neighboring before being lost: > — > — > > — Loss of laryngeals: Laryngeals were gradually eliminated through several developments: Intervocalic laryngeals were lost, with identical vowels contracting into long vowels. The sequences ih₂ and uh₂ developed into ya and wa. — h₃ may have had the same effect. Laryngeals adjacent to vowels were lost, often causing compensatory lengthening of a preceding vowel. — In syllabic resonant clusters, laryngeals were lost without lengthening. — Laryngeals occurring between consonants developed into ə. — All remaining laryngeals were lost.Centumization: The PIE palatovelars merged with the plain velars, eliminating the centum-satem distinction. - Glide insertion: A glide developed between high vowels and following vowels (iV, uV > iyV, uwV).Loss of postnasal voiced aspirates: PIE bʰ and dʰ were lost between a nasal consonant and a following vowel.Grassmann's law: When two voiced aspirated stops occurred within a word, the first lost its aspiration. It is not yet confirmed if this law existed in Proto-Tocharian.Devoicing of voiced aspirates: The remaining voiced aspirated stops became voiceless aspirates. — Devoicing in reduplicated forms: Stops that had lost aspiration through Grassmann’s law in reduplicated forms were also devoiced.ə elimination: The sequences əé and əó contracted into ö́ː. Remaining ə merged with a. — Word-final sibilant change: Word-final s became y in monosyllabic words.Lowering of u before y: uy became oy before consonants and word-finally.Loss of d before consonants: d was lost before consonants, except when occurring before syllabic resonants. — d was also possibly lost before rounded vowels.Labial coalescence: wi combined into u, while Kʷi became Ku.Vocalization of syllabic resonants: Syllabic resonants developed a new preceding ə (in contrast to the previous ə that had already merged with a). — Final nasal change: Word-final m became n. — Dental nasal assimilation: m became n before dental consonants. — Anaptyxis: ə was inserted into consonant clusters including a labial or velar consonant followed by st (Bst, Kst > Bəst, Kəst).Cluster simplification: Several consonant clusters containing stops and resonants were reduced by deleting one consonant (t(ʰ)sk, nsC, PsR > tk, sC, PR).Loss of final consonants: Word-final t, d, s, and n were lost. — . Final clusters of these consonants were also lost. — This sound change was inconsistently applied.Loss of final i: Word-final i was lost after dental consonants unless stressed. After the loss of i, remaining word-final t and s were lost.Dental affrication: Voiceless dental stops t(ʰ) followed by y or i developed into affricates. — . Word-final tsi simplified to si after vowels.ə raising: ə is raised to ɨ (written as "ä" by Tocharian scholars) — .Final oy monophthongization: Word-final oy became ẹː.Loss of final glides: Word-final y and w were lost after long vowels. — Additionally, w was lost in between a consonant and long uː.Final o raising: Word-final or and oː became ur and uː, respectively. — Major vowel shift: The vowel system underwent a chain shift: o and oː became ə and əː. — aː became oː. — əː became aː. — ə became ọ before rounded vowels through umlaut. — Word-initial ɨ became ə. — Palatalization: All consonants (as well as any s and n before said consonant) were palatalized before front vowels (i(ː), e(ː), and ẹ(ː)). — In addition, consonant + y sequences developed into palatalized geminates, except word-initially where gemination did not occur. This sound change was inconsistently applied. For example, i(ː) typically only palatalized dental consonants.Vowel harmonization: The sequence a…öː became o…oː.Initial glide formation: Word-initial i(ː), e(ː), and u(ː) developed initial glides (yi, ye, and wu). — Labiovelarization: Velars before u and in between u and another consonant developed labialization (Ku, uKC > Kʷu, uKʷC).High vowel merger: Short i, e, and u merged into ɨ, phonemicizing palatalization. — Loss of vowel length: All vowel length distinctions were eliminated, phonemicizing all changes to vowels based on length. — Unrounding of ö: ö became e.ɨ coloring: Before another vowel, ɨ was colored before a glide, giving iy, uw, and üwʲ.Retroflexion of palatal sibilants: sʲ became ṣ, except before tʲ and kʲ. — Affrication of d: d and dʲ became dz and dzʲ, except before consonants or after n. — Loss of aspiration: Remaining aspirated consonants lost aspiration. — Palatal siblation: tsʲ and k(ʷ)ʲ became tɕ, and dzʲ and g(ʷ)ʲ became dʑ. Later both affricates simplified to ɕ and ʑ. — Labial strengthening: m became b before resonants.Loss of voicing distinction: The contrast between voiced and voiceless obstruents was eliminated. — Palatalization complete: tʲ, sʲ, lʲ, and nʲ developed into tɕ, ɕ, ʎ, and ɲ respectively. — Reduction of w sequences: In non-final positions, several sequences involving w were simplified: awə became a. əwə became ə. owə, əwɨ, awɨ, and unstressed uwə became o. ewɨ became ọ.Initial resonant metathesis: In word-initial consonant clusters, resonant sequences were restructured: RɨC became ɨRC. Ruw became ɨRw. Rij became ɨRj. Rüwʲ became ɨRwʲ.Umlaut: ə, e, and u became ọ and ɨ became u when a back vowel followed later in the word. The diphthong äu became ọ only when ọ followed later in the word. ə became a when a followed later in the word and ə was unstressed.Velar nasal assimilation: nk became ŋk.Stop deletion in clusters: Stops were lost in certain clusters (PNC and CPN).Lateral assimilation: ln became ll.
Phonology
Vowels
Proto-Tocharian shows radical changes in its vowels from Proto-Indo-European (PIE). Laryngeal e-coloring and vowel lengthening occurs as it does in most other branches, however, length distinctions eventually disappeared. Prior to the loss of length distinction, all pairs of long and short vowels became distinct in quality, and thus have different outcomes. Many pairs of PIE vowels are distinguished in Tocharian only by the occurrence or non-occurrence of palatalization.
Reconstructing the changes between PIE and Proto-Tocharian vowels is fraught with difficulty, and as a result there are a large number of disagreements among different researchers. The basic problems are: Tocharian A and B are relatively sparsely attested. The extensive mergers of PIE stop consonants lead to many ambiguities in the potential etymologies underlying particular Tocharian words. The radical restructuring of the vowel system means that few potential sound changes can be rejected as unreasonable, no matter how unlikely they may look on the surface. A large amount of analogical change has occurred in both the nominal and verbal systems, making it difficult to identify which changes are regular.
Historically, the evolution of the Tocharian vowels was the last part of the diachronic phonology to be understood. In 1938, George S. Lane remarked of Tocharian that "the vocalism so far has defied almost every attempt that has been made to bring it to order",Lane, George S. "Problems of Tocharian Phonology". Language, Vol. 14, No. 1 (Jan. – Mar. 1938), pp. 20–38. and as late as 1945 still asserted: "That the subject [of palatalization] is a confused and difficult one is generally recognized—but so are most of the problems of Tocharian phonology."Lane, George S. "The Tocharian Palatalization (I)". Language, Vol. 21, No. 1 (Jan. – Mar. 1945), pp. 18–26. 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).Sieg, Emil and Wilhelm Siegling (1949), Tocharische Sprachreste, Sprache B. Heft 1. Gottingen: Vandenhoeck & Ruprecht. By 1960, the system was well-enough understood that Krause and Thomas's seminal work of that year is still considered one of the most important Tocharian grammatical handbooks.Ringe, Donald A, Jr. (1990). Review of Tocharian Historical Phonology and Morphology by Douglas Q. Adams. Language, Vol. 66, No. 2 (Jun. 1990).
Despite the apparent equivalence between the Tocharian A and B vowel systems, in fact a number of vowels are not cognate between the two varieties, and Proto-Tocharian had a different vowel system from both. For example, Tocharian A a reflects a merger of two Proto-Tocharian vowels that are distinguished in Tocharian B as e and o, while Tocharian B a reflects a stress-based variant of either Proto-Tocharian ā or ä, while Tocharian A preserves original ā and ä regardless of the position of stress.
As a general rule, Tocharian B reflects the Proto-Tocharian vowel system more faithfully than Tocharian A, which includes a number of changes not found in Tocharian B, e.g. monophthongization of diphthongs, loss of all absolutely final vowels, loss of ä in open syllables, and epenthesis of ä to break up difficult clusters (esp. word-finally) that resulted from vowel losses.
The following table describes a typical minimal reconstruction of Late Proto-Tocharian, which includes all vowels that are generally accepted by Tocharian scholars:
Front Central Back High i ä u Mid e ọ Low ā o
The following table describes a "maximal" reconstruction of Proto-Tocharian, following Ringe (1996):Ringe, Donald A. (1996). On the Chronology of Sound Changes in Tocharian: Volume I: From Proto-Indo-European to Proto-Tocharian. New Haven, CT: American Oriental Society.
Front Central Back High (i = ǝy) ǝ (u = ǝw) Mid ẹ ë ọ Low e ā o