Which one of the following was the earliest historical dynasty of Assam?

The earliest historical dynasty of Assam was the Narakas. The Narakas ruled parts of ancient Assam during the 4th and 5th centuries CE. They are known for their contributions to Assamese culture and history.

Option A: The Varmans were a dynasty that ruled Assam later in history.

Option C: The Salastambhas were not a historical dynasty of Assam.

Option D: The Palas were a dynasty that ruled parts of India but were not associated with early Assam.

So, the correct answer is Option B: Narakas, as they were the earliest historical dynasty of Assam.