The Tharus are the indigenous ethnic group who live in the northern part of Terai and inner Terai with a concentrated population in the middle and west. They approximately form 6.4% of total population.

Most of the Tharus have Mongoloid features with dark and semi- dark colors. They are aboriginal Terai settlers. Some also believe that Tharus came to Nepal from India during the Muslim invasion in the 12th and 13th century.

The Tharus have their indigenous dialect, known as ' Naja'. But they speak a mixture of local dialects, such as Prakriti, Bhojapuri, Mughali, Nepali, Urdu and Maithili.

Culture and Tradition :-  The Tharus believe in Animism. They do also celebrate Hindu festivals. There are normally two clans; Pradhan and Apradhan; the former is considered superior. Each of the Tharu family venerates its personal tutelary deity which is represented by a lump of earth mixed with multicolored cotton threads, crude sugarcane and a gold coin in the center. Each village has its own local gods and goddesses protecting the people.

Marriages among the Tharus, are monogamous. It is , however, strictly endogamous. Polyandry and polygamy are practiced sometimes. Rites and rituals linked with Tharu marriages are elaborate and complex. Most of the Tharu cremate their deceased. Others, however, bury them. There is a strange custom of keeping men face down and women face up during the burial. There is no apparent reason for it.