The scholars of the 18th century were struck by the far-reaching similarity of Sanskrit, both in grammar and vocabulary, to the classical languages of Europe. Intensive scientific studies that followed have established that Sanskrit and many Indian derivative languages belong to the family which includes English, German, French, Italian, Spanish, Celtic, Greek, Baltic, Armenian, Persian, Tocharian, and other Indo-European languages. Tamil, one of India's major classical language, descends from Proto-Dravidian languages spoken around the third millennium BCE in peninsular India. The earliest inscriptions of Tamil have been found on pottery dating back to 500 BC. Tamil literature has existed for over two thousand years and the earliest epigraphic records found date from around the 3rd century BCE. The evolution of language within India may be distinguished over three periods: old, middle and modern Indo-Aryan. The classical form of old Indo-Aryan was "Sanskrit" meaning polished, cultivated and correct, in distinction to "Prakrit" – the practical language of the migrating masses evolving without concern to proper pronunciation or grammar, the structure of language changing as those masses mingled, settled new lands and adopted words from people of other native languages. "Prakrita" became middle Indo-Aryan leading to "Pali" (the language of early Buddhists and Ashoka era in 200–300 BCE), "Prakrit" (the language of Jain philosophers) and "Apabhramsa" (the language blend at the final stage of middle Indo-Aryan). It is "Apabhramsa", scholars claim, that flowered into Hindi, Gujarati, Bengali, Marathi, Punjabi, and many other languages now in use in India's north, east and west. All of these Indian languages have roots and structures similar to Sanskrit, to each other and to other Indo-European languages. Thus we have in India three thousand years of continuous linguistic history recorded and preserved in literary documents. This enables scholars to follow language evolution and observe how, by changes hardly noticeable from generation to generation, an original language alters into descendant languages that are now barely recognisable as the same. Sanskrit has had a profound impact on the languages and literature of India. Hindi, India's most spoken language, is a "Sanskritised register" of the Delhi dialect. In addition, all modern Indo-Aryan languages, Munda languages and Dravidian languages, have borrowed many words either directly from Sanskrit ("tatsama" words), or indirectly via middle Indo-Aryan languages ("tadbhava" words).