The Sena Empire is a Hindu dynasty that rules from Bengal through the 11th and 12th centuries.
At its peak ,the empire covers much of the northeastern region of the Indian subcontinent.
The Senas are all Brahmanas.
Some Senas later become Brahma-Kshatriyas as evidenced through their surname, which is derived from the Sanskrit, for "army".
The Senas belong to the 'Gaur Kayastha' caste of the Chitraguptvanshi Kayastha.
The Brahma-Kshatriya Senas (those who were Brahmanas first and became Brahma-Kshatriyas afterwards) revert to Brahmanas later/concurrently.The dynasty's founder is Hemanta Sen, who is part of the Pala Dynasty until their empire begins to weaken.
He usurps power and styles himself king in 1095.
His successor Vijay Sen (rules from 1096 to 1159) helps lay the foundations of the dynasty, and has an unusually long reign of over 60 years.
Ballal Sena conquers Gaur from the Pala, and becomes the ruler of Bengal Delta as well as making Nabadwip the capital.
Lakshman Sen succeeds Ballal Sena in 1179 and rules Bengal for approximately 20 years.
He expands the Sena Empire to Assam, Odisha, Bihar and probably to Varanasi.
In 1203–1204, the Turkic general Bakhtiyar Khilji attacks Nabadwip.
Though he defeats Lakshman Sen, he failed to conquer Bengal.
