You can read about the disintegration of the Mughal empire after Aurangzeb here: http://www.historydiscussion.net/empires/later-mughals-and-d...

The Marathas never controlled an "undivided India" given the extent of their empire at it's peak: https://www.mapsofindia.com/history/maratha-empire.html

Not to mention, even Akbar did not have the North east and the southernmost parts of India.

The rise of the Sikh empire, and the Deccan sultanate also limited the extent of the later Mughal and Maratha kingdoms.

I did not question that these empires had their time. But the notion of undivided India as united as one under the Mughals at the time right before the British arrived is wrong. Ancient times do not affect contemporary affairs, or in this case affairs of 1750s are not affected by the Maurya dynasty's claim on some version of modern day India/Pakistan/Bangladesh.