The Hindus among Maithili regions of Nepal and India celebrate Chhath festival, which is also known as Surya Shasti. The Sun, considered as the god of energy and of the life force, is worshiped during the Chhath festival to promote well-being, prosperity and progress. In Hinduism, Sun worship is believed to help cure a variety of diseases, including Leprosy, and helps ensure the longevity and prosperity of family members, friends, and elders.
Chhath Parba is observed for 4 days from Kartik Shukala Chaturthi to Kartik Shukala Saptami. This festival falls in October or November in the English Calendar. Chhath is also celebrated in on Chaitra Shashti, the early summer about March or April, and is called Chaiti Chhath. They include holy bathing, fasting and abstaining from drinking water (Vratta), standing in water for long periods of time, and offering Prasdhad (prayer offerings) and Arghya to the setting and rising sun.
Chhath Festival is mostly celebrated in Terai part of Nepal.
There is a legend that Chhath was celebrated because the times of Mahabharat, Draupdi, the wife of Pandava Kings, performed Chhath Puja. Once during the long exile from their kingdom, thousands of wandering hermits visited their hut. Being devout Hindus, the Pandavas were obliged to feed the monks. But as exiles, the Pandavas were not in a position to offer food to so many hungry hermits. Seeking a quick solution, Draupadi approached Saint Dhaumya, who advised her to worship Surya and observe the rituals of the Chhath for prosperity and abundance.
In Nepal, Chhath is celebrated in the Terai region, especially in the eastern part. While it is celebrated auspiciously in Rani Pokhari of Kathmandu, some of major pounds in Birgunj and Biratnagar etc. It is a festival of Joy and sentiments. Devotees worship sun and offer them with sacred water and fruits and Prasad’s. There is a huge fair on the banks of rivers and ponds.