To become ruler of this region, a man supposedly marched so quickly that only eighteen horsemen could keep up with him when he conquered its city of Nadia. Three lieutenants, Ali Mardan, Shiran, and Iwaz, took control of this region when its leader and Ali Mech left in a campaign along the Tea-Horse route to the Chumbi Valley. This region’s calendar likely starts with the accession of (*) Shashanka to the throne of the Gauda (-5[1])Kingdom. A dynasty in this non-Delhi region that pledged allegiance to the Ghurid dynasty was named for its founder Bakhtiyar Khalji. The last independent Nawab of this region, (10[1])Siraj ud-Daulah, held prisoners in the Black Hole of Calcutta. (10[1])For 10 points, name this region split between a country formerly known as East Pakistan and India. ■END■ (10[1])