The word ' Pongal' comes from the Tamil literature. It means 'to boil.' It is an ancient South India festival, particularly celebrated in Tamil Nadu. It is a four-day harvest festival that is celebrated in the month of January-February (Thai) during the solar equinox following harvesting of crops such as rice, sugarcane, turmeric, etc. The first day is called the Bhogi festival; the second day is called Thai Pongal; the third day is called Mattu Pongal; while the fourth day is called Kaanum Pongal.
According to Hindu mythology, Lord Shiva once asked Basava (Bull) to visit the Earth and to ask the human every day for an oil massage and a bath. However, the Basava (Bull) announced that they eat every day and have a bath of oil once a month. This made Lord Shiva angry and he cursed the Basava (Bull) to live forever on Earth.
Basava (Bull) was expected to plough the fields and help people produce more food. Hence, people celebrate this festival with crops and cattle after harvesting to mark this event.
The festival's history can be traced back to the Sangam Age as the 'Dravidian Harvest Festival.' But some historians say that the festival dates back at least 2,000 years. It was known as Thai Niradal.
According to legends, unmarried girls prayed for the country's agricultural prosperity during this festive season and performed penance during Margazhi's Tamil month for this reason. They abstained from consuming milk and milk products and didn't oil their hair all month long. They specifically refrain from using harsh words. Early morning ceremonial bath are also conducted as part of the penance ceremony.
It's simply a harvesting festival or it can be called as a 'thanksgiving' festival because this festival is celebrated to thank the Sun God and Lord Indra for helping farmers get better yielding crops. As we know India is an agricultural country and most of the festivals are inclined towards nature. Pongal is also referred to as the Uttarayan Punyakalam, which in Hindu mythology bears special significance and is considered to be extremely auspicious.