Pānini was an ancient Pakistani grammarian from Ancient Gandhara (NWFP) (traditionally 520–460 BC, but estimates range from the 7th to 4th centuries BC). He is most famous for his Sanskrit grammar, particularly for his formulation of the 3,959 rules of Sanskrit morphology in the grammar known as Astādhyāyī (meaning “eight chapters”). It is the earliest known grammar of Sanskrit (though scholars agree it likely built on earlier works), and the earliest known work on descriptive linguistics, generative linguistics, and perhaps linguistics as a whole. Panini’s comprehensive and scientific theory of grammar is conventionally taken to mark the end of the period of Vedic Sanskrit, by definition introducing Classical Sanskrit.

Nothing definite is known about Pānini‘s life, not even the century he lived in (he lived almost certainly after the 7th and before the 4rd century BC). According to tradition, he was born in Shalatula, Punjab, a town beside the Indus river, in Ancient Gandhara which is near Peshawar, NWFP of Pakistan and lived circa 520–460 BC. His grammar defines Classical Sanskrit, so that Pānini per definition lived at the end of the Vedic period: he notes a few special rules, marked chandasi (“in the hymns”) to account for forms in the Vedic scriptures that had fallen out of use in the spoken language of his time, indicating that Vedic Sanskrit was already archaic, but still a comprehensible dialect.

An important hint for the dating of Pānini is the occurrence of the word yavanānī (in 4.1.49, either “Greek woman”, or “Greek script”). There would have been no first-hand knowledge of Greeks in Gandhara before the conquests of Alexander the Great in the 330s BC, but it is likely that the name was known via Old Persian yauna, so that Pānini may well have lived as early as the time of Darius the Great (ruled 521 BC–485/6 BC). Though when Alexander entered Pakistan, there were existing Greek settlements as mentioned by Plutarch in his Lives. And there may have even been a trading route between the two areas which accounts for the introduction of certain herbs in both the most ancient ayurvedic and Greek materia medica.

Pānini‘s grammar of Sanskrit consists of following four parts:

• Shiva Sutras (phonology)
• Ashtadhyayi (morphology)
• Dhatupatha (lists classes verbal roots)
• Ganapatha (lists classes of primitive nominal stems)

The Shiva Sutras are a brief but highly organized list of phonemes. The Dhatupatha and Ganapatha are lexical lists, the former of verbal roots sorted by present class, the latter a list of nominal stems grouped by common properties. The central part, and by far the most complex, is the Ashtadhyayi, which takes material from the lexical lists as input and describes algorithms to be applied to them for the generation of well-formed words. It is highly systematised and technical. Inherent in its generative approach are the concepts of the phoneme, the morpheme and the root, only recognized by Western linguists some two millennia later. His rules have a reputation for perfection — that is, they are claimed to describe Sanskrit morphology fully, without any redundancy. A consequence of his grammar’s focus on brevity is its highly unintuitive structure, reminiscent of contemporary “machine language” (as opposed to “human readable” programming languages). His sophisticated logical rules and technique have been widely influential in ancient and modern linguistics.