Purnia ()(also romanized as Purnea) is the fourth largest city of Bihar and emerging as the biggest economic hub in North Bihar. It serves as the administrative headquarters of both Purnia district and Purnia division in the Indian state of Bihar. It is well known for its favourable climate like Darjeeling and have abundance amount of resources for human settlements and economic activities. Total geographical area of Purnia Urban Agglomeration is which is next only to Patna. Population density of the city is 3058 persons per km sq. making it the 4th largest city of Bihar by population. It is nearly 315 km from Patna, as well as 171 km from Siliguri, 90 km from Bhagalpur. It is 640 km from Guwahati (Approx.) and 450 km from Kolkata, the capital of the adjacent state of West Bengal and the largest city in East India. Purnia district covers 3202.31 sq. km of the state of Bihar. The Indian Army, Indian Air Force, and three of five branches of India's Central Armed Police Forces – the Border Security Force (BSF), the Sashastra Seema Bal (SSB), and the Indo-Tibetan Border Police (ITBP) – have bases around the district. Several possible origins for the name Purnia have been proposed. The name may originate from the Sanskrit word Purna–Aranya, which means "complete jungle". Purnia could also be an altered form of the old name Purania, derived from the word purain or Lotus, which is said to have grown on the Kosi and Mahananda rivers. The city's name is also romanized as Purnea. Purnia is part of the Mithila region. Mithila first gained prominence after being settled by Indo-Aryan peoples who established the Mithila Kingdom (also called Kingdom of the Videhas). During the late Vedic period (c. 1100–500 BCE), Videha became one of the major political and cultural centers of South Asia, along with Kuru and Pañcāla. The kings of the Videha Kingdom were called Janakas. The Videha Kingdom was later incorporated into the Vajjika League, which had its capital in the city of Vaishali, which is also in Mithila.