Explanation:

Shashanka was the first independent king of a unified polity in the Bengal region, called the Gauda Kingdom and is a major figure in Bengali history. He reigned in 7th century AD, some historians place his rule between circa 600 C.E and 636/7 C.E. Whereas other sources place his reign between 590 and 625 C.E. He is the contemporary of Harsha and of Bhaskaravarman of Kamarupa. His capital was at Karnasubarna, in present-day Murshidabad in West Bengal. The development of the Bengali calendar is often attributed to Shashanka because the starting date falls within his reign.