SANSKRIT AND INDO-EUROPEAN 33 these archaisms was the very first to reach the borders of India, and that later successive waves of Indo-Aryan invaders con- fined it into a narrow space in the mountain valleys of the North-West frontier, where it has survived in isolation to this day. The history of In do- Ary an begins with the first introduction of Aryan speech into India, but between this event and the composition of the first recorded document of Indo-Aryan, the hymns of the Rgveda, a considerable period must have elapsed. This is clear from the fact that in the text of the Rgveda itself, although historical allusions are not uncommon, there is no reference anywhere to the fact of the migration, nor any definite indication that it was still remembered. Linguistic reasons also compel us to assume such a period, since the number of lin- guistic (mainly phonetic) changes that have taken place since the common Indo-Iranian stage is considerable. No doubt the beginnings of dialectal cleavage go back to the Indo-Aryan period, but there is no doubt that the bulk of the characteristic changes of Indo-Aryan and Iranian respectively have taken place after the complete separation of the two groups, that is to say, after the Aryan invasion of India. Some of the more important changes that affected Indo- Aryan during this period may be briefly listed : (i) /A and zh become A ( — Ir. j and z), (2) j and i are confused as j ( = Ir. j and z ) , (3) a single group ks results from the two combinations k- -s and s -K9 ; these are kept apart in Iranian, (4) Aryan voiced groups of the type gzh, bzh are replaced by unvoiced As, ps (Skt, dipsa - : Av. diwza-), (5) Aryan z is elided in all positions (Skt. medhd cf. Av. mazdd ), (6) Elision of Aryan z before d gives rise to cerebral d (nidd-) and this, in conjunction with other combinatory changes {as tan, vit f katana-) is the beginning of a new series of consonants previously foreign to Aryan, as well as to the rest of Indo-European. (7) s ( s ) is elided between two consonants (< dbhakta , s-aor.). (8) All final consonant groups are simplified and only the first remains (Skt. vdk : Av. vdxs ). (9) A tendency begins to weaken the aspirates dh and bh to h (ihd ' here ' : Av. iSa, but Pa. idha has retained the older form). (10) The Aryan diphthongs at, au are turned into the simple vowels e } 5 . This list of changes is impressive enough, and of great import- ance for the future history of Indo-Aryan, and a reasonable
