Purnia is the fourth largest city of Bihar and is emerging as the largest economic hub in North Bihar. It serves as the administrative headqua…Purnia is the fourth largest city of Bihar and is emerging as the largest 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 has an abundance of resources for human settlements and economic activities.