Complex sentence: Najm ud Daulah, son of Mir Jafar was a Nawab of Bengal between 1765-1766, he was subordinate to the forces of the British East India Company which was establishing itself in the subcontinent.
Split into simpler sentences: Najm ud Daulah, son of Mir Jafar was the Nawab of Bengal from 1765 to 1766. He was subordinate to the forces of the British East India Company which was establishing itself in the subcontinent.