Though the culture of India is one, one that is based on Hinduism,there are minor differences in practices by the people.
The four castes, which is a loose and incorrect translation of the word Varna, follow uniform code, though they might be quite far off from each other, despite no written scripture for such practices.
However one finds some differences in the practices followed by them,though they follow the general spirit of the Vedas and Smritis.
Take the instance of Brahmins .
The Brahmins of South India, Iyers and Iyengars do not generally have surname following their names as is the case in North India.
The terms Iyer and Iyengars are unique to Tamil Nadu.
Then one case divisions among the Brahmins in South India.
In Tamil Nadu, there are Iyers, with sub groups like Ashtasahasrama, Brahathcharanam,Vadama, and Vathima.
In Andhra one has Mulukanadu and the like.
In Karnataka also there are subdivisions.
Why such differences from the North indian Brahmins and among the Brahmins of South Indian themselves?
There are some references.
One states that Sage Viswamitra had his fifty sons ostracised to Dravida Desa for questioning his authority and these people intermarried with the Dravidas.
One of their descendants, Apasthamba compiled the Vedas in yet another form in the form of Sutras, called the Apasthamba Sutras.
This sutra incorporates some practices of the Dravidians like the wearing of Mangal Sutra in a Marriage.
This practice is not present in Vaidika system of marriage.
Then we have the difference in the Veda Paatas, the specific branch and the recitation.
One finds the near absence od the Ataharva Veda in the South and the Shukla Yajur is followed by a few people in Tamil Nadu.
In Tamil Nadu, one finds Krishna Yajur and Sama Veda being practiced more.
In Andhra and Karnataka , Rig Veda and Krishna Yajur, in Andhra Rig And Sama Veda.
Though there is yet another reference of Brahmins having been in the South around 5000 BC and even before this, why there is such a difference in practices?
Did Brahmins live in the South or did they migrate from the North?
“Battles mentioned in the Rig Veda, whether between those called Aryans or Dasyus, are largely between the “five peoples” (pancha manava). These five are identified as the Turvashas, Yadus, Purus, Anus and Druhyus, which the Puranas describe as oRiginating from the five sons of Yayati, an early Vedic king in the lunar dynasty descended from Manu, and the son of Nahusha. These peoples, both Dasyus and Aryans, are also called Nahushas in the Rig Veda.(*24) Of the five the main people of the Rig Veda are the Purus who are usually located on the Sarasvati river or the central region. The Yadus are placed in the south and west in Gujarat, Rajasthan and Maharashtra up to Mathura in the north. The Anus are placed in the north. The Druhyus are placed in the west and the Turvasha southeast. These are the directions given to them in the Puranas.
In the original Puranic story there were two groups of people, the Devas and Asuras, or godly and ungodly people, who had various conflicts. Both had Brahmin gurus, the Angirasas for the Suras (Devas) and the BhRigus for the Asuras. Both these Brahmin groups we might add were responsible for many teachings in ancient India, including the Upanishads. The battles between the Devas and Asuras involved a struggle between their gurus.
King Yayati, the father of the five Vedic peoples and a follower of the Angirasas, had two wives, Devayani, the daughter of Shukra of the BhRigu seers, and Sharmishta, the daughter of Vrisha Parvan, king of the Asuras. Turvasha and Yadu were sons of Yayati by Devayani of the BhRigus. Anu, Druhyu and Puru were sons of Yayati by Sharmishta of the Asuras.(*26) Yayati’s story shows that the five Vedic people were born of an alliance of Aryan and Asuric kings, and their Angirasa and BhRigu seers.
Vrisha Parvan and Shukra appear to have come from southwest India, Gujarat, as the BhRigus were descendants of Varuna, God of the sea, and have always been associated with this region of India (for example, their city BhRigukaccha or modern Baruch near Baroda). In the Puranic story their territory bordered on that of Yayati, who happened upon both Devayani and Sharmishta, while hunting.
Hence three of the original five Vedic peoples had Asuric blood in them through their mother. Puru, whose group ultimately predominated, had Asuric blood, whereas the Yadus, who were most criticized in Vedic and Puranic literature, had no Asuric blood but rather that of the Brahmins. In this story we see that both groups of people – thought by the Aryan invasion theory to be the invading Aryans and the indigenous peoples – had the same religion and ancestry.
These five peoples were styled either Arya or Dasyu, which mean something like good or bad, holy or unholy according to their behavior. Their designation can shift quickly. The descendants of an Aryan king can be called Dasyu or its equivalent (Rakshasa, Dasa, Asura, etc.), if their behavior changes.
For example, in the most important battle in the Rig Veda, the famous battle of the Ten Kings (Dasarajna), victorious Sudas, regarded as a Puru king, and located on the Sarasvati river, includes among his enemies called Dasyu groups of the five Vedic peoples like the Anus, Druhyus, Turvashas, and even Purus.(*27) However, the sons of Sudas themselves fall and in Brahmanical and Puranic literature are themselves called Rakshasas or demons for killing the sons of the great rishi Vasishta.(*28) Meanwhile the Kavashas, a seer family, listed among the defeated enemies of Sudas (*29) appear again in the Brahmanas and Upanishads as the chief priests of the famous dynasty of Kuru kings, particularly Tura Kavasheya, the purohit for King Janamejaya.(*30) The BhRigus, who were among those defeated by Sudas, appear as prominent teachers in later Vedic and Puranic lore as already noted. Such shifts would be impossible if Aryan and Dasyu were simply racial terms. Aryans and the Dasyus are not a racial or linguistic but a religious or spiritual divide, which changes along with human behavior.”
The Puranas make the Dravidians descendants of the Vedic family of Turvasha, one of the older Vedic peoples. These ancient historians did not feel any need to limit the Vedic people to one linguistic group. The Vedas portray the large region of north India which must have been as complex culturally then as today. In fact the Puranas regard the Chinese, Persians and other non-Indic peoples to be descendants of Vedic kings. The Vedas see all human beings as descendants of Manu, their legendary first man.
Thus one sees that the Brahmins were the residents of Dravida and there was also a group that moved in, sent in by Viswamitra(History of the Tamils by PT.Srinivasa Ayengar).
Thus one can assert that the Brahmins of the South are the descendants of Yayati of Lunar Dynasty.