Proto-Indo-Iranian language

Proto-Indo-Iranian or Proto-Indo-Iranic[1] is the reconstructed proto-language of the Indo-Iranian/Indo-Iranic branch of Indo-European. Its speakers, the hypothetical Proto-Indo-Iranians, are assumed to have lived in the late 3rd millennium BC, and are often connected with the Sintashta culture of the Eurasian Steppe and the early Andronovo archaeological horizon.

Proto-Indo-Iranian was a satem language, likely removed less than a millennium from the late Proto-Indo-European language, its ancestor, and in turn removed less than a millennium from the Vedic Sanskrit of the Rigveda, its descendant. It is the ancestor of the Indo-Aryan languages, the Iranian languages, and the Nuristani languages.

Descriptive phonology

Proto-Indo-Iranian consonant segments
Labial Coronal Palatal Velar Laryngeal
dental/alveolar post-alveolar first second
Plosive voiceless *p *t *ĉ *č *k
voiced *b *d *ĵ *ǰ *g
aspirated * * *ĵʰ *ǰʰ *


*s *š *H
voiced (*z) (*ž)
Nasal *m *n
Liquid (*l) *r *
Semivowel *y *w
PII vowel segments
High *i *ī *u *ū
Low *a *ā

In addition to the vowels, *H, and * could function as the syllabic core.

Two palatal series

Proto-Indo-Iranian is hypothesized to contain two series of stops or affricates in the palatal to postalveolar region.[2] The phonetic nature of this contrast is not clear, and hence they are usually referred to as the primary or first series (*ĉ *ĵ *ĵʰ, continuing Proto-Indo-European palatovelar *ḱ *ǵ *ǵʰ) and the second or secondary series (*č *ǰ *ǰʰ, continuing Proto-Indo-European plain and labialized velars, *k, *g, *gʰ and *kʷ, *gʷ, *gʷʰ, in palatalizing contexts). The following table shows the most common reflexes of the two series (Proto-Iranian is the hypothetical ancestor to the Iranian languages, including Avestan and Old Persian):[3][4]

PII Sanskrit Proto-Iranian Avestan Old Persian Nuristani
*ĉ ś ([ɕ]) *ts s θ ċ ([ts]) / š
*ĵ j ([ɟ]) *dz z d j ([dz]) / z
*ĵʰ h ([ɦ])
*č c *č č č č
*ǰ j ([ɟ]) *ǰ ǰ ǰ ǰ / ž
*ǰʰ h ([ɦ])


Proto-Indo-European is usually hypothesized to have had three to four laryngeal consonants, each of which could occur in either syllabic or non-syllabic positions. In Proto-Indo-Iranian, the laryngeals merged as one phoneme /*H/. Beekes suggests that some instances of this /*H/ survived into Rigvedic Sanskrit and Avestan as unwritten glottal stops as evidenced by metrics.[5]


Like Proto-Indo-European and Vedic Sanskrit (and also Avestan, though it was not written down[6]), Proto-Indo-Iranian had a pitch accent system similar to present-day Japanese, conventionally indicated by an acute accent over the accented vowel.