Around the sixth-seventh centuries, there began the formation of cultural units which later came to be known as Karnataka, Maharashtra, Orissa, Rajasthan, Tamil Nadu, etc.
The identity of the various cultural groups is recognized by both foreign and Indian sources.
The Chinese traveller Hsuan Tsang mentions several nationalities.
The Jaina texts of the late eighth century notice the existence of eighteen major peoples or nationalities and describe the physical features of sixteen. They reproduce samples of their language and say something about their character. Vishakhadatta, an author of about the ninth century, speaks of different regions inhabited by peoples different in customs, clothing, and language.
Since the seventh century, a remarkable development takes place in the linguistic history of India, the birth of Apabhramsha, the final stage of the middle Indo-Aryan. This language is placed roughly halfway between Prakrit that preceded it and modern Indo-Aryan languages that succeeded it. It roughly covers the period from AD 600 to 1000. Extensive Jaina literature was written in this language towards the end of this period.
Glimpses of modern languages are traceable in both Jaina and Buddhist writings in Apabhramsha. Buddhist writings from eastern India show faint glimmerings of Bengali, Assamese, Maithili, Oriya, and Hindi. Similarly, the Jaina works of the same period reveal the beginnings of Gujarati and Rajasthani. In the south, Tamil was the oldest language, but Kannada began to grow at about this time. Telugu and Malayalam developed much later.
It seems that each region came to develop its own language because of its isolation from the other. When the Gupta empire broke up, several independent principalities rose, and this naturally hindered countrywide contacts and communication. The decline of trade meant lack of communication between the people of the various regions, and this promoted the growth of regional languages.
Regional scripts became more prominent in ad seventh century and later. From Maurya to Gupta times, although the script changed to some degree, more or less the same script continued to be used throughout the greater part of India. Thus, a person who has mastered the script of the Gupta age can read inscriptions of that period from different parts of the country, but from the seventh century onwards, every region had its own script, and therefore it is not possible to read post-Gupta inscriptions from different parts without mastering the regional scripts.