It is impossible to confirm the origin of a culture and the date of its origin. Different tribes, classes, and societies gradually combined over a period of time and a transformed society had evolved. This is the evolution of a society.
Andhra society is one of the ancient societies of India. One can encounter several tales about Andhras in epics like Mahabharatam and Ramayanam, in great puranas, and Budhdhist Jataka Tales. This confirms the ancient nature of Andhra society.
Andhras and Kalingas (ka'Limgulu) supported the Kauravas during the battle between Kauravas and Pandavas (the Bharata yudhdham). Sahadeva defeated the kingdoms of Pandya, Dravida, Odhra, Kerala, Andhra, and Kalinga while performing the Rajasooya yajna. This is depicted in the Mahabharatam. Chanoora (ca'NooruDu) was killed by Srikrishna in Madhura. Harivamsapuranam corroborates the fact that Chanoora was the king of Karoosa Desa (karooSa dESam) (on the North side of Vindhya and on the North banks of Yamuna river) and was an Anhdra (Andhrudu) too.
Ramayanam depicts an interesting tale. Viswamitra condemned the "Naramedha Yagam", freed Sunassepu (SunaSSEpu, the yajna paSuvu), and adopted him as his son. Viswamitra's children diliked this act by thier father and were cursed. Then Viswamitra's children migrated towards east and south. It is understood from this tale that these children of Viswamitra were Andhras (a'mdhrulu).
A tribe called "Andhras" arrived at the banks of Yamuna river during the Mahabharata war (1500 BC). This is clearly described in the epic.
Mahabharata war has a prominent place in the ancient history. Several kings of different tribes fought in this battle. Several thousands of soldiers lost their lives. Kauravas were destroyed. Innumerable number of tiny kingdoms mushroomed. Locust infestation destroyed crops on the banks of Ganges and Yamuna rivers. People inhabiting those regions migrated 300 miles away to south. Chandogyopanishat (Ca'mdOgyOpanishad) confirms this. Iatreya (aitarEya bra'hmaNam) Brahmanam tells us that Andhras lived on the south side of Vindhya along with Pundrapulinda Sabara Mootibas (punDrapulimda Sabara mootibulu). Chandogyopanishad and Itareya Brahmanam were written in 1000 BC.
Andhras were nomads for several centuries. Some tribes (classes) migrated and others did not want to do so and remained in their older settlements. During 700 BC some Andhra tribes inhabited the Salvadesa (sa'lvadESamu) on the banks of Yamuna River. The tale of Apastambarushi (a'pastambaRushi) explains this. Apastamba rules (a'pastamba gruhya sootra'lu) have been widely in practice among Andhra Brahmin families today. A single Rushi was the teacher (a'ca'rya) of each tribe. Apastamba was one such teacher. Apastamba wrote these rules in Salvadesam on the banks of Yamuna river. After Apastamba's death the Andhra tribes crossed the Vindhya mountains, reached the South, and merged with the other Andhra tribes.
Some of those Andhras who came to the south settled on the west side of Vindhya mountains (present Northern regions of Hyderabad). Another tribe crossed the Eastern Ghats over Orissa and reached the Kalinga Desam. "Serivanijo" Jataka tale explains that Andhras built the "ANDHAKAPURAM" on the banks of "Tel" (tEl) river.
Jataka tales were written during 200-250 BC. Tel river is a subriver of Mahanadi in Orissa. This confirms that one of the Andhra tribes migrated this way. The people in this tribe are Kalingas (ka'Limgulu). The books cited above describe the Andhras and Kalingas as two different branches of a single tribe. Sometimes these two words (Andhras and Kalingas) are used as synonyms interchangeably.
Andhra tribes established relationships with Naga, Yaksha, and Dravida tribes of Vindhya mountains who already were living there then. Telugu, Tamil, and Kannada are Dravidian languages. Rayalaseema was the first settlement of Tenugu (identify here! TENUGU is used here) people. Later Telangana was occupied. The name "Tenugu" transformed into "Telugu". From "Telugu" words like "Telagalu", "Telangana", "Telanganyulu" (a subsect of Andhra Brahmins), and "Teligiri" originated. A tribe called "Tailang" (taila'ng) in Burma is proposed to be related to Telugu people.
Tenugu (tenugu) is the meaning for those who travel towards south. In Tamil and Kannada "ten" means south side (dakshina dikku).