Supaul district is a district of Bihar with its administrative head quarters located at Supaul town. Supaul has a rich history. Since the Vedic era till today, the Supaul district has been a part of Mithilanchal. According to the Hindu Mythology this region was known as the Matsya Kshetra meaning fishery area. The present day Supaul district comprised of the two oldest democracies in the Buddhist era namely Angutaran and Apadnigam. Earlier, it was a part of Saharsa district, a part of the Mithila Region. For the first time Mithila came into the lime light after the Indo-Aryan peoples settled there and they established the Mithila Kingdom as well. Moreover, the Mithila Kingdom is also popularly known as Kingdom of the Videhas. During the late Vedic period (C. 1100-500 BCE.), the region of Videha came out as one of the major political and cultural centers of South Asia, along with Kuru and Pancala. The place of Supaul was carved out from the Saharsa district on 14th March, 1991 and at the same year Supaul was emerged as a separate district in the map of Bihar. It is located on the Indian side of the Indo-Nepal border.

Randhir Prasad Verma, an illustrious Indian police officer was born in the year 1952 at Jagatpur village in the district. He was post humously honoured by the valour award Ashok Chakra. In his honour the Government of India also issued a commemorative postage stamp in 2004.

Geographically, the district lies at 26°12'N latitude, 86°59'E longitude and 34 m Altitude. In the year 2021, there was a total 5.54% forest area of total geographical area. The district encompasses a geographical area of 2,425 sq. kms. and it is bounded by  Nepal on the north, Araria district on the east, Madhepura and Saharsa districts on the south and Madhubani district on the west. Every year the natives of the district face the flood problem because the Kosi River flows through the Supaul district. Most of its rainfall occurs in the monsoon season. The actual rainfall in the district was 2079.8 mm in the year of 2021-22.

Administration wise, the district is divided into 4 sub-divisions namely Supaul, Birpur, Triveniganj and Nirmali. There are 1 Lok Sabha seat and 5 Assembly constituencies in the district. Moreover, the district comprises 3 towns and 551 villages. The administrative language in the district is Hindi.

According to 2011 census the district has a population of 22,29,076 out of which 11,55,283 are males and 10,73,793 are females. The district has a sex ratio of 929 females for every 1000 males. During the year 2001-2011 the population growth rate in the district was 28.66% out of which 28.05% were males and 29.31% were females. As per 2011 census the major religions in the district are Hindu and Muslim with 81.20% and 18.36% of the total population. The population density in the district is 919 persons per sq. km. According to 2011 census the principal languages in the district are Maithili and Urdu with 76.31% and 9.30%. In the year 2020 the number of live births in the district was 71,280 out of which 37,077 were males and 34,189 were females. In the same year the number of deaths in the district was 6,245 out of which 3,832 were males and 2,411 were females.

The economy of the district is solely dependent on agriculture. Every year a huge chunk of revenue comes from the agricultural products grow in the district. The chief agricultural product in the district is Paddy. It has a few factories of plywood and furniture for the reason that industrially, the district is not well developed. Natives of the district also earn their livelihood from the dairy farm and egg farm which hep in its economy to a great extent. In 2006 the ministry of Panchayati Raj declared Supaul as one of the country's 250 most backward districts and currently receiving funds from the Backward Regions Grant Fund Programme (BRGF). In the year 2011-12 the gross domestic product in the district was Rs. 3,01,331 lakhs at current price and Rs. 1,74,736 lakhs at constant prices in the year 2004-05. In the year 2011-12 the net domestic product in the district was Rs. 2,71,678 lakhs at current price and Rs. 1,55,203 lakhs at constant prices in the year 2004-05.

Now-a-days some reputed educational institutions are established in the district. It has also some renowned madrassas namely Madrassa Mazharul Uloom, Madrassa Rahmania, Jamia Islamia Riyazul Uloom, Jamia Salfia Miftahul Uloom, etc. As per 2011 census the literacy rate in the district is 57.67% including 69.62% are males and 44.77% are females. The number of literates in the district is 10,33,283 out of which 6,47,672 are males and 3,85,611 are females.

Raj Kumar Singh, an eminent Indian politician and former home secretary of Indian government in the year 2013 was born on 6th November, 1953 at Basbitti in the Supaul district. He is a member of Bharatya Janata Party.

The district has some sets of tourist places which allure many travellers from across the country. Dharahara is a village in the district has many trees of several generations. The place is full of mango and litchi trees. Vishnu Mandir, a pious place in the district has a famous Vishnu temple which allures devotees from several parts of the country. Tintolia is a temple of Goddess kali. It is a very popular place to visit by the pilgrims. Some other not able centres of attraction in the district are Kosi River, Kapileshwar Mandir, Hanuman Mandir, etc.