Prehistory to early 19th century
The following table lists estimates for the population of India (including what are now Pakistan and Bangladesh) from prehistory up until 1820. It includes estimates and growth rates according to five economic historians, along with interpolated estimates and overall aggregate averages derived from their estimates.Estimates of historical world population

Year	Aggregate average	Period	Average
 % growth
/ century
Population	% of World population
10,000 BC	1,000	0.83%	Stone Age	30.28
4000 BC	1,000,000	30.83%
2000 BC	13,000,000	37.143%	Bronze Age	26.25
500 BC	25,000,000	41.70%	Iron Age	
400 BC	26,000,000	43.96%
200 BC	31,000,000	47.63%	Maurya era	
1 AD	35,000,000	35.56%	Classical
era	
200	41,000,000	36.15%
400	47,000,000	40%
500	50,000,000	43.58%
600	53,000,000	48.83%	Early
medieval
era	
700	60,000,000	56.67%
800	64,000,000	55%
900	70,000,000	53.34%
1000	79,000,000	30%
1100	83,000,000	35%	Late
medieval
era	
1200	86,000,000	36.67%
1300	91,000,000	38.34%
1400	97,000,000	30%
1500	105,000,000	21.67%
1600	140,000,000	23.33%	Early modern era	
1650	170,000,000	26.15%
1700	140,000,000	20%
1750	183,000,000	21.53%
1800	200,000,000	20%
1820	210,000,000	19.09%
The population grew from the South Asian Stone Age in 10,000 BC to the Maurya Empire in 200 BC at a steadily increasing growth rate, before population growth slowed down in the Early Medieval Era up to 700 AD, and then started decreasing the up to 1500 AD.

Under Mughal Empire, India experienced a high economic and demographic upsurge, due to Mughal agrarian reforms that intensified agricultural production. 15% of the population lived in urban centres, higher than the percentage of the population in 19th-century British India and contemporary Europe up until the 19th century. Those estimates were criticised by Tim Dyson, who considers them exaggerations. According to Dyson, urbanisation of the Mughal empire was less than 9%

Under the reign of Akbar (reigned 1556–1605) in 1600, the Mughal Empire's urban population was up to 17 million people, larger than the urban population in Europe. By 1700, Mughal India had an urban population of 23 million people, larger than British India's urban population of 22.3 million in 1871. Nizamuddin Ahmad (1551–1621) reported that, under Akbar's reign, Mughal India had 120 large cities and 3,200 townships. A number of cities in India had a population between a quarter-million and half-million people, with larger cities including Agra (in Agra Subah) with up to 800,000 people and Dhaka (in Bengal Subah) with over 1 million people. Mughal India also had a large number of villages, with 455,698 villages by the time of Aurangzeb (reigned 1658–1707).
what was population of India during Mauryan Era?
It was around 31,000,000 during Maurya Era (200BC) .