Thanks to Murali Sham for bringing this historical lanuage to our attention – Deskarati –
Sanskrit is a member of the Indo-Iranian sub-family of the Indo-European family of languages. Its closest ancient relatives are the Iranian languages Old Persian and Avestan.
In order to explain the common features shared by Sanskrit and other Indo-European languages, many scholars have proposed migration hypotheses asserting that the original speakers of what became Sanskrit arrived in what is now India and Pakistan from the north-west some time during the early second millennium BCE. Evidence for such a theory includes the close relationship of the Indo-Iranian tongues with the Baltic and Slavic languages, vocabulary exchange with the non-Indo-European Uralic languages, and the nature of the attested Indo-European words for flora and fauna.
The earliest attested Sanskrit texts are Hindu texts of the Rigveda, which date to the mid-to-late second millennium BCE. No written records from such an early period survive. However, scholars are confident that the oral transmission of the texts is reliable: they were ceremonial literature whose correct pronunciation was considered crucial to its religious efficacy.
From the Rigveda until the time of Pāṇini (fl. 4th century BCE) the development of the Sanskrit language may be observed in other Vedic texts: the Samaveda, Yajurveda, Atharvaveda, Brahmanas, and Upanishads. During this time, the prestige of the language, its use for sacred purposes, and the importance attached to its correct enunciation all served as powerful conservative forces resisting the normal processes of linguistic change. However, there is a clear, five-level linguistic development of Vedic from the Rigveda to the language of the Upanishads and the earliest Sutras (such as Baudhayana).
The oldest surviving Sanskrit grammar is Pāṇini’s Aṣṭādhyāyī (“Eight-Chapter Grammar”). It is essentially a prescriptive grammar, i.e., an authority that defines correct Sanskrit, although it contains descriptive parts, mostly to account for some Vedic forms that had become rare in Pāṇini’s time.
The term “Sanskrit” was not thought of as a specific language set apart from other languages, but rather as a particularly refined or perfected manner of speaking. Knowledge of Sanskrit was a marker of social class and educational attainment in ancient India and the language was taught mainly to members of the higher castes, through close analysis of Sanskrit grammarians such as Pāṇini. Sanskrit, as the learned language of Ancient India, thus existed alongside the Prakrits (vernaculars), also called Middle Indic dialects, and eventually into the contemporary modern Indo-Aryan languages.
Sanskrit, as defined by Pāṇini, had evolved out of the earlier “Vedic” form. The beginning of Vedic Sanskrit can be traced as early as 1500–1200 BCE (for Rg-vedic and Indo-Aryan superstrate in Mitanni). Scholars often distinguish Vedic Sanskrit and Classical or “Pāṇinian” Sanskrit as separate ‘dialects’. Though they are quite similar, they differ in a number of essential points of phonology, vocabulary, grammar and syntax. Vedic Sanskrit is the language of the Vedas, a large collection of hymns, incantations (Samhitas), theological and religio-philosophical discussions in the Brahmanas and Upanishads. Modern linguists consider the metrical hymns of the Rigveda Samhita to be the earliest, composed by many authors over several centuries of oral tradition. The end of the Vedic period is marked by the composition of the Upanishads, which form the concluding part of the Vedic corpus in the traditional view; however the early Sutras are Vedic, too, both in language and content. Around the mid-1st millennium BCE, Vedic Sanskrit began the transition from a first language to a second language of religion and learning.
For nearly 2,000 years, a cultural order existed that exerted influence across South Asia, Inner Asia, Southeast Asia, and to a certain extent, East Asia. A significant form of post-Vedic Sanskrit is found in the Sanskrit of the Hindu Epics —the Ramayana and Mahabharata. The deviations from Pāṇini in the epics are generally considered to be on account of interference from Prakrits, or “innovations” and not because they are pre-Paninean. Traditional Sanskrit scholars call such deviations ārṣa(आर्ष), meaning ‘of the ṛṣis’, the traditional title for the ancient authors. In some contexts, there are also more “prakritisms” (borrowings from common speech) than in Classical Sanskrit proper. Buddhist Hybrid Sanskrit is a literary language heavily influenced by Middle Indic, based on early Buddhist prakrit texts which subsequently assimilated to the Classical Sanskrit standard in varying degrees.
According to Tiwari (1955), there were four principal dialects of classical Sanskrit: paścimottarī (Northwestern, also called Northern or Western), madhyadeśī (lit., middle country), pūrvi(Eastern) and dakṣiṇī (Southern, arose in the Classical period). The predecessors of the first three dialects are even attested in Vedic Brāhmaṇas, of which the first one was regarded as the purest (Kauṣītaki Brāhmaṇa, 7.6)