V P

 Vaikhānasa tradition and the Pāñcarātra tradition originated, especially the story of Vikhanasa and Pañcarātra.

There are two beautiful but different origin stories.

1. The story of Vikhanasa — Vaikhānasa Agama

According to the Vaikhānasa tradition, Lord Nārāyaṇa is the ultimate source.

At the beginning of creation, Brahmā received from Nārāyaṇa the knowledge of how the Lord should be worshipped. The teaching was extremely vast. Over time, Brahmā found that this enormous body of knowledge was difficult to preserve.

So Brahmā went to Naimiṣāraṇya, performed severe tapas and meditated upon Lord Viṣṇu. Through that tapas he regained the divine knowledge of worship and abridged it into a form suitable for practice.

At this point he is known as Vikhanasa.

Vikhanasa then transmitted this knowledge to four great sages:

Atri

Bhṛgu

Marīci

Kāśyapa

They became the principal teachers through whom the Vaikhānasa Agama was transmitted. 

That is why it is called Vaikhānasa — the tradition associated with Vikhanasa.

2. Then comes Pāñcarātra

There is another famous story.

At one point the Vedas were taken away by demons, leaving Brahmā unable to perform worship in the usual Vedic manner. In his difficulty, he approached Lord Nārāyaṇa.

The Lord then taught a method of worship centred on His divine mantras. In the well-known Pāñcarātra account, this teaching was given over five nights.

Hence:

pañca = five

rātra = nights

→ Pāñcarātra = the teaching of the five nights.

The TTD also describes the traditional account in which Nārāyaṇa teaches Pāñcarātra to Ananta, Garuḍa, Viśvaksena, Brahmā and Śiva. 

The fascinating point

So we should not think of Vaikhānasa and Pāñcarātra as two different Gods or two competing religions.

Both are Vaishnava Agamic traditions centred on the worship of Śrīman Nārāyaṇa. The two traditions developed different ritual systems and textual lineages. Sri Vaishnava tradition has historically respected both. Vedānta Deśika, for example, explicitly refers to devotees worshipping the Lord through both the Pāñcarātra and Vaikhānasa paths. 

And there is a lovely connection  about Tirupati: Tirumala's Venkateśvara temple follows the Vaikhānasa system, whereas Tiruchanur Padmavati temple follows Pāñcarātra.