The Tibetans speak of Sanskrit as the language of the gods. They say it is one of four Indian languages, i.e.,

1. Sanskrit, the ‘beautifully constructed,’ which is the language of the gods,
2. Apabhramsha, the language of secret signs,
3. Prakrit, the common or corrupted language, and
4. Paishachi, the language of flesh-eating demons or spirits.

Sanskrit is an Indo-European language, but more specifically it belongs to the Indo-Iranian branch, along with Persian. The earliest speakers of Indo-Iranian are known as the Aryans. Originally coming from somewhere north of the Caucasus, the Aryan tribes migrated into Central Asia, and then became separated: some of them settling in Iran, and some in India. The arrival of the Aryans in India is thought to have occurred at some time during the latter half of the second millennium BCE.

The earliest known form of the Indo-Aryan language is Vedic Sanskrit, beginning with the hymns of the Ṛg Veda, the oldest parts of which date from 1000BCE. After the Vedas came the Brahmanas, which were prose commentaries on the Vedic ritual, and include the Upanishads.

Classical Sanskrit owes much to the brilliant grammarian Pāṇini (4th century BCE) who analyzed and codified the grammar of the Sanskrit language so comprehensively in his Aṣṭsādhyāyī that his pronouncements were deemed definitive.

It was to be much longer, however, before the great period of Classical Sanskrit literature began. As ordinary people came to rely more and more on regionally distinct descendents of Sanskrit, the so-called Prakrit languages, for their everyday communication, Sanskrit became the language of administration and writings on science and other academic topics. Just as Latin was the lingua franca of the educated classes during the Middle Ages, Sanskrit became the language of the learned throughout India.

This is the form of Sanskrit called Classical. It was influenced to some extent by the common speech, but it still adhered to Panini’s rules. It is the language of India’s great epics, the Mahabharata and Ramayana (completed beginning of 1st millennium CE) , and of the great dramatists and poets, such as Kalidasa (early 5th century CE) and Shamkhara.