Siddharthnagar district (Hindi: सिद्धार्थनगर ज़िला, 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.