It would've been even smaller if it wasn't for the devastating consequences of European imperialism. These countries were left in a piss poor state, lack of education and healthcare etc, resulting in a long period of high birth rates with exponential growth.
Check the graph below [2] you can clearly where most damage happened, during the main occupation period (1850s to 1950s). Britain had falling birth rates (prosperity) but they were constantly high in India (poverty). Birth rates have been on a steep decline only after independence. Yet empire apologists somehow claim that it was a net good for India :)
[1] https://ourworldindata.org/grapher/population-by-country
[2] https://www.gapminder.org/tools/#$model$markers$line$data$fi...
Europeans talking about high population, human rights and global warming is a joke
In 1960s villages didn't have access to medicine or doctors. So people used to produce 5-7 children so atleast 1-2 went into adulthood.
But as medicine became more easily accessible all 5-7 children ended up in adulthood leading to population increase.
Nowadays I see max 2 children in villages.
Because of this: https://en.wikipedia.org/wiki/Indo-Gangetic_Plain
An exaggerated relief map showing its sheer size and flatness: https://i.redd.it/5qv0bvyrd9h01.png
Extremely high fertility rates.