The Mithila Kingdom was later incorporated into the Vajji confederacy, which had its capital in the city of Vaishali, which is also in Mithila. During the Mughal rule, Purnia was an outlying military province, and its revenue was mostly spent on protecting its borders against tribes from the north and east. After the capture of Calcutta in 1757, Purnia's local governor raised a rebellion against Siraj ud-Daulah. In 1765, the district became a British possession, along with the rest of Bengal. On February tenth, 1770 The district of Purnia in modern history was formed by the East India Company.