This Onam (Thiruvonam) festival is celebrated in Kerala. This is the biggest festival of Kerala. It falls in Malayaalee Month of Chingam (August-September). It marks the homecoming of Raajaa Bali. Carnival of Onam in Kerala lasts for 10 days and brings out the best of their culture and tradition. Keralites all over the world will be celebrating these ten days with a lot of spirit and happiness. This is the harvest festival also. Onam is a special occasion when the Sun is in his own House and Moon is in his own Nakshatra (some say it is the Nakshtra of Vishnu, some say it is the Nakshatra when Vaaman was born and the Tri-Vikram put His 3 steps in this world. Here also the Sun is in his own Raashi (Sign) and ruling it (Soorya Raashi starting from Sinh) and Moon is in his starting Raashi (Lunar Signs) which is Capricorn to Cancer).

Onam is a celebration of 10 days, which starts on Atham day. People put flower mats in front of their houses, to welcome the King Mahabali. They wish to please the spirit of their King by depicting that his people are happy and wish him well. The second day, Thiruvonam is the biggest and the most important day of this festival. It is believed that King Mahabali visits his people on the second day. There will be competition for the laying of flower mats; They will wear new dresses, will be visiting almost all temples which they can, and the most important thing is the grand lunch they will be having on the Thiuruvonam day. Whatever may happen they will not miss the Grand lunch. There is a saying in Malayaalam that "Kanam Vittu Onam Unnanam" which means "We should have the Thiruonam lunch even if we have to sell all our properties". They give that much importance to the lunch on the Thiruonam day. The Onam celebration is an occasion for people to remind themselves of all the pervasive nature of divine. A message is not something to be said; it's something to be lived. But if you try to encapsulate the message of Onam into one word, it is "happiness".

Legend Behind Onam Festival
A long long time ago, an Asur (demon) king called Mahaa  Bali ruled Kerala. Mahaa Bali was the son of Virochan and grandson of Prahlaad, the devout son of demon King Hiranyakashyap. He was a noble, generous righteous and powerful king who ruled with justice, wisdom and generosity. His bravery and strength of character earned him the title of "Mahaabali Chakravarthy" or Mahaabali - the King of Kings. Although he was an asur, no devta was as noble, in thought or action, as him. During his ruling time it is said that people didn't even lock their house in the night because, there was no thieves, no corruption, and no betrayal. All the people were considered equal; all were living with great happiness. No one had any threats, challenges or danger to life. There was no falsehood or fraud. No one cheated others. People never lied. There were no wrong measuring equipments and weights. No one cheats or wrongs the neighbor. There was no poverty, sorrow or disease in the reign of King Mahaa Bali and everybody was happy and content. And all people lived united, without the difference of rich and poor. All were facing a good time because of all these all the people loved him and he glowed like a jewel among them.

He was a wise, benevolent and judicious ruler and beloved of his subjects. Soon his fame as an able king began to spread far and wide, but when he extended his rule to the Heavens and the netherworld, the gods felt challenged and began to fear his growing powers. Presuming that he might become over-powerful, Indra pleaded to Vishnu to curtail Mahaa Bali's powers.

Vishnu knew Mahaa Bali's weakness that he was a great donor and he would never refuse to give anything whatever he would ask from him. So He was born in Aditi's, mother of Devtaa, house as a dwarf. Since He was a dwarf He was known as Vaaman. Mahaa Bali was doing a Yagya at that time and iyt was on completion. He approached Mahaa Bali and asked for alms. Pleased with the form of the dwarf Braahman, Mahaa Bali asked Him what did He want? The Vaaman asked for a simple gift - three paces of land. Mahaa Bali was surprised to hear such a strange request. He said - "O Braahman, You should have cared at least for my status. I am such a great King and you are asking me only three feet land. Ask something by giving which I can feel at least some pride. Ask me so much money which will be enough for your coming many generations." But Vaaman said - I am a Brahmchaaree, so I will not have any progeny. I need only three feet land just to do my worship. I am satisfied with it."  and the king agreed to it.

Now the Emperor's preceptor, Shukraachaarya warned him against promising Him His alms, for he had realized that the seeker was no ordinary boy. He was the Master of the Tri-Lok. But as Mahaa Bali had already promised Him to give three feet land he could not have gone back, so he did. He was happy that he was extending the favor to God who gives everybody. So he firmly declared that there is no greater sin than going back from one's promise. He kept his word. Vishnu in the guise of Vaaman then increased his stature and with the first step covered the sky, blotting out the sky and stars, and with the second, straddled the Heaven. Now Vaaman asked him - "Where should I keep my third foot?" Bali bowed down to Him and said politely - "You give to all and you take from them. Whatever you gave me you have taken. Now remains my body, so take this also," and he lay down on the ground down facing. Vishnu Got very pleased with him, so he appointed him the King of Rasaatal and p[romised him to appoint him Indra in the next Manvantar. Till then he should live there happily. At that time Bali asked Him a boon that since he loved his people very much, if he could come to see them once a year. Vishnu granted him a boon.

Onam is the celebration of the same day that marks the homecoming of King Mahaa Bali. It is the day when a grateful Kerala pays a glorious tribute to the memory of this benign king who gave his all for his subjects. That is why Onam is celebrated by wearing new clothes and resolving to lead a new life of truth, piety, love, and humility.

Once, Brahmaa Jee went to Thirupati and worshipped Lord Venkateshwar by lighting two lamps. He prayed the Lord that the lamps should glow nonstop till Kali Yug exists. The Lord granted his wish and said that He would give Darshan to devotees in the form of Jyoti on all Thiruvonam days at Thirumalai Vaiyaavoor and till that Jyoti Darshan continues, the lights lit by Brahmaa Jee would be alive. Brahmaa Jee then came here to this place and worshipped the Lord and got Darshan in the form of Jyoti.
http://www.dharsanam.com/2008/03/thirumalai-vaiyaavoor-sri-prasanna.htm\

Onam day is Hayagreev's Jayantee too. .He is considered the purity of knowledge and wisdom. Shree Lakshmee Hayagreev (the Lord with the horse's face) Haya-horse: Greevaa-neck: This Avataar of Hayagreev took place to restore the Ved to Brahmaa Jee. Naaraayan incarnated as Hayagreev, appeared as the white Horse faced, faultless Sphatik hued form, Sattwa Moorty, with Divya Tej, and lustrous form and destroyed the Asur and restored the Ved to Brahmaa Jee. This Avataar was made during Avanee month, Shravan Nakshtra, and on Poornimaa Tithi.

When the Pralaya was about to end, Bhagvaan out of His dirt from His ear drums made two small solid balls and dropped on the Lotus leaf and Brahmaa activated the Praan Vaayu in them, which gave life to these two balls, as Madhu and Kaitabh. These Asur grew up. Brahmaa Jee started his creation and Ved were snatched away by these two Asur. When the most compassionate Lord, wished to please the Asur, without killing them, asked them as to what they wanted as a boon. These two Asur said - "You are saying otherwise, we can give you what you want, instead that you grant us any boon." That is it! The Lord decided to kill them. They said - "You can kill us only where there is no cover for the sky?" The Lord immediately took Hyagreev Avataar and removed His cloth on the thighs, put them on His thighs and killed them. Bhagvaan's legs house the Earth and the space/sky. Since the Lord removed the cloth from His thighs and killed them there, He still complied with what they challenged Him. What they thought was impossible to happen, He could make it happen with no effort. He, thus saved the Ved and saves the world.

The moral is: Tamas, Rajas Gun are to be destroyed to reach Him Ashwa Shirase Namah
http://www.parakalamatham.org/node/3

Kerala Legend Onam
Mahaa Bali (short form Maaveli). There is no mention about the territory which was under his regime except he ruled all the three worlds and all his subjects were very happy and highly prosperous. Nobody told lies, there was no theft and in short it was a golden era. He was born as the son of Virochan and Devaambaa. His grand-father was Prahlaad the great devotee of Mahaa Vishnu. Although born as an Asur and his great grand-father was Hiranyakashyap, an ardent devotee of Lord Shiv. The Itihaas and Puraan are written with exaggeration since they are all legends which cannot be totally believed or totally rejected as false. Indra who is the Lord of Heavens who experienced the defeat from Bali could not tolerate the defeat. Hence he approached Lord Vishnu to help him to stop the just rule of Bali because of which only he could succeed in defeating Indra. Although, during Bali's rule, people were very happy and there was neither theft nor any one spoke lies. Even people lived without any anxieties. Vishnu is generally said to be favoring the Devataa. Further Vishnu might have thought that an Asur should not rule over Heaven and with Bali, there will be two Indra etc.

However, we cannot rely fully on these stories as they are said to have happened in Krit or Tretaa Yug. However Onam, Atir and Vishu were the three days on which if the husbands do not go to the wife's house, that could be a reason for divorce. However Vishu and Atir have taken back seat and Onam has become a State Festival of Kerala. Whatever it may be Keralites considered Atir for celebration of Lord Shiv and Onam for Vishnu. This shows that among Hindu of Kerala there were many who were Shaivites and equally were Vaishnavites. That is the reason why these two Nakshatra have prefix of Thiru , thus calling Athir by adding prefixing Thiru became Thiru-Vathir, and Onam by adding prefix Thiru became Thiru-Vonam. ( Thiru is a Tamil word even now in use for which Shree is the equivalent Sanskrit word. Who knows, when Malayaalam wants to drift away from her mother Tamil, a day might not be far if Thiru-Vonam is called as Shree-Onam and Thiruvathira as Shree-Athir. Why, I say this is because I have seen lot of writing in Old Malayaalam inscribed on rocks in which most of the words coincide with the present day Tamil.

According to Bartholomio in olden days Thiru-Vonam used to be celebrated for 8 Days. There used to be Kayyaamkali, Cheripporu, Onaththallu, Olappandu Kali, (Thala Pandu Kaliu ) etc. All front side of the houses which they call as Muttam used to be washed and cleaned with cow dung, all mud pots to be removed and replaced with new ones. The youths used to divide themselves and stand opposite each other and play Bow and Arrows. Although the arrows are made blunt still the force with which it is sent from a bow will injure the receiver. These games have similarity with the games played by Greek and the Romans. Those who ruled Venad used to go to Shree Padmnaabh Swaamee Temple and receive new clothes and a bow and arrows from the Chief Priest. Although most of these practices have vanished now still the major event of performing Poojaa to Thrikkakkaayappan still exists. In the Malanad there are 13 Divya Des (Divine places) of Vaishnavites in that Namaalwaar who is one among the top alwars, has said. Hence this temple is one of the important temples of Vaishnavites.

There is also a place called Puramkarai. The deity in Thrikkalkkarai used to be called as---- and the Devee used to be called ---. might be so called because of the fact Vaaman who was called as Trivikram or because with His three feet placed on the head He made Bali to go to Paataal, thus ending his regime. When Kulsekhar Permaal was ruling Kerala , he made many as Naaduvaazhis of Kerala. Kaalkkarai was an important town of which was ruled by such Naaduvaazhis.

Even now the Vaishnavites in Tamil Naadu celebrate Onam. As per legends when Indra was defeated by the righteous Bali, the scared Indra went to Vishnu and requested Him to help in regaining the Swarg lok. Vishnu knew that Bali was a king who was highly virtuous and also the grandson of his Bhakt Prahlaad. However, since He was pro-Devtaa, He wanted to help Indra. Defeating Bali was an impossible task even for gods by fighting, because he was very pious and highly virtuous . Hence the cunning Vishnu hatched a plan to disguise himself as a dwarf Braahman boy called Vaaman (Tri-Vikram), and went to Bali's palace.

The Daitya Guru, Sage Shukraachaaraya, knew the bad intentions of Devtaa and hence entreated Bali not to accept the request of that dwarf Braahman boy. However, Bali did not pay heed to his words. He was adamant in hearing the request of the Braahman boy and asked the boy as to what he wanted; for which the boy told that he had no landed property and requested the Mahaaraaj to give him three feet of land to stay. As it was a custom, which is almost forgotten now, in those days, Bali was about to perform the oath of giving by Dhaaraa from a pitcher, Shukraachaarya placed one of his eye on the opening of the pot. Since water was not going out from the opening of the pot, the boy used Darbhaa grass blade and pushed the obstacle back in the spout of the pot. This pierced one eye of Shukraachaarya and bled. Water started coming out and Bali completed the oath of giving away the Daan of three feet land asked by the boy. Once the oath was taken. Lord expanded His body and took His one foot to the Heavens and with the second foot, he measured the Bhoo Lok and with the third foot the Underworld.

Bali requested the Lord to give him a place to lead the rest of his life, for which the Lord agreed and asked him to go to Paataal Lok. Bali asked the Lord again to allow him to come to the world and see his subjects and to know their welfare at least ones a year which the Lord granted. So on Onam day people of Kerala and even some from Tamil Naadu celebrate this day. Onam has now become a state festival. They wear new clothes and enjoy by playing to greet their erstwhile Mahaaraaj.

Vaishnavites in Tamil Naadu still celebrate Thiru-Vonam. During this time there used to be special Poojaa and feasts in their houses. PERIYAAZHVAR who lived during AC 9 the century has written thus :- The meaning as I presume is that we shall wear the clothes which you wore and thrown as waste, and eat the waste after you eat , and also wear the Tulasee garland which thou used and after which sleeping on the snake bed called Aanand, and prostrate 100 times wishing you all the best. Thirupati Venkateshwar Swamy has the same importance as Thrikkaakkarai Temple.

Although Onam in Tamil Naadu is celebrated by only Vaishnavites. Even in Dharmasthal some Jains also celebrate Onam. In Thulu Naadu (Tulu Naadu (Tulu : is the Tulu speaking region spread over to parts of present Karnaatak and Kerala States of India. It consists of the South Kannada and Udupee districts of Karnaatak and the Northern parts of the Kasaragod district of Kerala up to Chandragiri River. Mangalore and Udupee are the important cities.) Shaivites and Vaishnavites celebrate it as in Kerala. People of Gudalur and Ooty also celebrate Onam. Apart from this in Kurg, which is full of Kodav also celebrate Onam.