Siddharthnagar district is one of the 75 districts of Uttar Pradesh state in Northern India. Naugarh town is the district headquarters. Siddharth Nagar district is a part of Basti division. The district is known for the ruins of the Shakya Janapada, at Piprahwa. 22 km from the district headquarters Naugarh. According to the Government of India, Siddharthnagar district is one of the Muslim concentrated districts in India on the basis of the 2001 census data on population, socio-economic indicators and basic amenities indicators.

The district was named after prince Siddhartha, the pre-enlightenment name of Buddha, as he spent his early years (till the age of 29) in Kapilavastu, parts of which included territory in this district.

Siddharthnagar district was carved out on 29 December 1989 by bifurcating Basti district. The new district comprised the northern part of the erstwhile Basti district.Siddharthnagar district encompasses the village of Piprahwa (22 km from Naugarh), best known for its archaeological site. A large stupa and the ruins of several monasteries are located within the site at Piprahwa. Ancient residential complexes and shrines were uncovered at the adjacent mound of Ganwaria.

Some scholars have suggested that modern-day Piprahwa-Ganwaria was the site of the ancient city of Kapilavastu, the capital of the Shakya kingdom, where Siddhartha Gautama spent the first 29 years of his life, according to Buddhist texts such as the Pāli Canon.Others suggest that the original site of Kapilavastu is located 16 kilometres (9.9 mi) to the northwest, at Tilaurakot, in what is currently Kapilvastu District in Nepal.

Notable individuals from the region have included Ahmad Hussain Akrahra, Khajuria Baadshah Mehdi Hasan Khan Khajuria, freedom fighter Qazi Adeel Abbasi, Qazi Iftekhar Ahmad, Haji Noorul Haque (Naugarh Bazar) and Maulana Abdul Qayyum Rahmani. Saddened by communal riots and massacre during the partition of India, Maulana Abdul Qayyum Rahmani, an eminent leader of Congress, abandoned politics and settled down in his native village of Dudwania in his later years. Freedom fighter Prabhudayal Vidyarthi, arrested at Sevagram and confined in an isolation cell from 1942 to 1945 in Nagpur Jail, Maharashtra, came from Siddharthnagar district. The bridge on Farenda Naugarh-Barhni Shravasti Road is named Prabhu Dayal Vidyarthi Van Ganga Bridge to honour him.

Siddharthnagar district lies between 27°N to 27°28’N and 82°45’E to 83°10’E. It is part of Purvanchal. The district borders Nepal’s Kapilvastu district on the north and Rupandehi district on the northeast. Otherwise it is surrounded by other districts of Uttar Pradesh: Maharajganj on the east, Basti and Sant Kabir Nagar on the south, and Balrampur on the west. Siddarthnagar’s area is 2,752 km2.

In 2006 the Ministry of Panchayati Raj named Siddharthnagar one of the country’s 250 most backward districts (out of a total of 640).It is one of the 34 districts in Uttar Pradesh currently receiving funds from the Backward Regions Grant Fund Programme (BRGF).

According to the 2011 census, Siddharthnagar district has a population of 2,553,526, roughly equal to the nation of Kuwait or the US state of Nevada.This gives it a ranking of 164th in India (out of a total of 640).The district has a population density of 882 inhabitants per square kilometre (2,280/sq mi).Its population growth rate over the decade 2001-2011 was 25.17%.Siddharth Nagar has a sex ratio of 970 females for every 1000 males, and a literacy rate of 67.81%.The minority population is about 27% of the total population of the district. Siddharth Nagar is a category “A” district; that is, it has socio-economic and basic amenities parameters below the national average.