Analysis of information sources in references of the Wikipedia article "Classical languages of India" in English language version.
To find out the written specimens of the Assamese literature, we are to go back to the period of the songs and aphorisms composed by the Buddhist Siddhacharyas between the 8th and the 12th centuries A.D.
Classical Sanskrit was elegantly described in one of the finest grammars ever produced, the Aṣṭādhyāyī ("Eight Chapters") composed by Pāṇini (c. 6th–5th century BCE).
Assamese literary tradition dates to the 13th century. Prose texts, notably buranjis (historical works), began to appear in the 16th century.
The Bengali linguists Suniti Kumar Chatterji and Sukumar Sen suggested that Bengali had its origin in the 10th century ce, deriving from Magahi Prakrit (a spoken language) through Magahi Apabhramsha (its written counterpart).
The Bengali scholar Muhammad Shahidullah and his followers offered a competing theory, suggesting that the language began in the 7th century CE and developed from spoken and written Gauda (also, respectively, a Prakrit and an Apabhramsha).
Marathi literature is the oldest of the Indo-Aryan literatures, dating to about 1000 ce.
Charyapads are considered as the first written specimen of Assamese literature.
…a Chinese-Sanskrit Dictionary compiled by Li-Yen bears testimony to the fact that at least 51 Bangla words made their way into that dictionary…The Chinese-Sanskrit dictionary, compiled in the 8th Century CE, included or rather was compelled to include words of a third language, i.e., Bangla.
Charyapads are considered as the first written specimen of Assamese literature.
The Marathi language's first known inscription dates back to around 2200 years ago, found in the Naneghata inscription, where the term "Maharathino" was used. This inscription, written in the Brahmi script, proves that the language must have existed at least a few centuries before.
The Indo-Aryan language in Kamarupa had differentiated by the 7th-century, before it did in Bengal or Orissa. ... The earliest forms of Assamese in literature are found in the ninth-century Buddhist verses called Charyapada, and in 12-14th century works of Ramai Pundit (Sunya Puran), Boru Chandidas (Krishna Kirtan), Sukur Mamud (Gopichandrar Gan), Durllava Mullik (Gobindachandrar Git) and Bhavani Das (Mainamatir Gan). In these works, Assamese features coexist with features from other Modern Indian Languages.
