The legend of Churning of Ocean:

The legend of Churning of Ocean of Milk (950 AD to 1120 AD): An Explanation

Indra, the King of Svarga, while riding on the elephant Airavata, came across Sage Durvasa who offered him a special garland given to him by a nymph. Indra accepted the gift and placed it on the trunk of the elephant as a test to prove that he was not an egoistic deva. The elephant, knowing that Indra had no control over his own ego, threw the garland on the ground. This enraged the sage as the garland was a dwelling of Sri (fortune) and was to be treated as a prasada or religious offering. Durvasa cursed Indra and all devas to be bereft of all strength, energy, and fortune.

In battles following the incident, the Devas were defeated and the Asuras, led by Bali, gained control over the universe. The Devas sought Vishnu's help, who advised them to treat the Asuras in a diplomatic manner. The Devas formed an alliance with the Asuras to jointly churn the ocean for the nectar of immortality and to share it among themselves. However, Vishnu told the Devas that he would arrange for them alone to obtain the nectar.

The churning of the Ocean of Milk (Parkadal or Bay of Bengal) was an elaborate process: Mount Mandara was used as the churning rod, and Vasuki, a nāgarāja who abides on Shiva's neck, became the churning rope. The Asuras demanded to hold the head of the snake, while the Devas, taking advice from Vishnu, agreed to hold its tail. When the mountain was placed in the ocean, it began to sink. Vishnu, in the form of Kurma (turtle – guides devas on navigating the ship in the ocean), came to their rescue and supported the mountain on his shell. The Asuras were poisoned (war) by fumes emitted by Vasuki. Despite this, the Devas and the Asuras pulled back and forth on the snake's body alternately, causing the mountain to rotate, which in turn churned the ocean.

The Samudra Manthana (travelling to and fro in the ocean by ships) process released a number of things from the Ocean of Milk (Par kadal – today Bay of Bengal). One of them was the lethal poison (war) known as Halahala. However, in some versions of the story, the poison (war) escaped from the mouth of the serpent king as the demons and gods churned. This terrified the gods and demons because the poison (war) was so powerful that it could destroy all of creation. The Devas then approached Shiva for protection. Shiva consumed the poison (war) to protect the three worlds and in the process burnt his throat. As a result, his throat turned blue and he was henceforth called Neelakantha (the blue-throated one; "neela" = "blue", "kantha" = "throat" in Sanskrit). This story is about the war between Cholas (Devas) and others (Asuras) to improve trade and amass wealth (950 AD to 1120 AD).

Ratnas – Wealth amassed by Cholas (Devars) and Asuras (others/Buddhists) in trade wars (950 AD to 1120 AD).

Sagar Manthana

All kinds of herbs were cast into the ocean and fourteen Ratnas (gems or treasures) were produced from it and were divided between the Asuras and the Devas. Though usually the Ratnas are enumerated as 14, the list in the scriptures ranges from 9 to 14 Ratnas. Most lists include: According to the quality of the treasures produced, they were accepted by Shiva (because of consuming the poison/war), Vishnu, Maha rishi's (for accepting Kamadevi), or Surabhi, which was given by Vishnu, the Devas and the Asuras.

There were three categories of Goddesses (amassed wealth) which emerged from the ocean;

1. Lakshmi: the Devi of Fortune and Wealth, who accepted Vishnu as Her eternal consort.
2. Apsaras: various divine nymphs like Rambha, Menaka, Punjisthala etc., who chose the Gandharvas as their companions.
3. Varuni: taken - somewhat reluctantly (she appeared dishevelled and argumentative) - accepted the Asuras.

Likewise, three types of supernatural animals appeared: The herds, cows, elephants and horses captured during war.

1. Kamadhenu or Surabhi (Sanskrit: kāmadhuk): the wish-granting cow, taken by Brahma and given to the sages so that the ghee from her milk could be used for Yajna and similar rituals.
2. Airavata and several other elephants, taken by Indra.
3. Uchhaishravas: the divine seven-headed horse, given to Bali.

Three valuables were also produced:

1. Kaustubha: the most valuable ratnam (divine jewel) in the world, worn by Vishnu.
2. Parijat: the divine flowering tree with blossoms that never fade or wilt, taken to Indraloka by the Devas.
3. Sharanga: a powerful bow, given to Lord Vishnu.

Additionally produced were;

1. Chandra: the moon which adorned Shiva's head. The lunar race or dynasty was captured.
2. Dhanvantari: the "Vaidya of the Devas" with Amrita, the nectar of immortality. (At times, considered as two separate Ratna)
3. Halahala: the poison (war) swallowed by Shiva.

This list varies from Purana to Purana and is also slightly different in the Ramayana and Mahabharata. Lists are completed by adding the following Ratna:

1. Shankha: Vishnu's conch
2. Jyestha: the goddess of misfortune
3. The umbrella taken by Varuna
4. The earrings given to Aditi, by her son Indra
5. Kalpavriksha plant
6. Nidra or sloth

The am?ta

Various scenes from the samudra manthan (the ships) episode

Finally, Dhanvantari, the heavenly physician, emerged with a pot containing the am?ta, the heavenly nectar of immortality. Fierce fighting ensued between the Devas and the Asuras for it. To protect it from the Asuras, Garuda took the pot and flew away from the battlefield.

The Devas appealed to Vishnu, who took the form of Mohini and, as a beautiful and enchanting damsel, distracted the Asuras; then, she took the am?ta and distributed it among the Devas, who drank it. An Asura named Rahuketu disguised himself as a deva and drank some nectar. Due to their luminous nature, the Sun god Surya and the moon god Chandra noticed this disguise. They informed Mohini who, before the nectar could pass the Asura's throat, cut off his head with her discus, the Sudarshana Chakra. From that day, his head was called Rahu and his body Ketu, which both later became planets. The story ends with the rejuvenated Devas defeating the Asuras.