Historical data especially concerning the prosperity of Vijaynagar empire is nebulous. By portugese accounts, the revenues of the entire Vijaynagar empire were equal to the mughal province of Gujarat which explains why Sultanate of Gujarat could browbeat Bahamani sultanate which easily kept Vijaynagar down. It also explains why small kingdom of Orissa could fight Sultanate of Bengal on its northern frontier and Vijaynagar empire on its southern frontier at same time. Vijaynagar empire did play an important role in preserving our culture and added to its richness but its overall affect on Indian history is shadowy.
As for British imperialism and the affect of colonial droughts. Between 1841 and 1881, the population of Madras presidency doubled as it escaped major droughts(except 1877) and British policies increased the agriculture output esp series of canals (they would do the same for Punjab later on). Madras Presidency from 5.6% of India 's population in 1841 was in 1881, 12% of population. That also explains that similar percentages in medieval times would explain that the Vijayanagar empire 's effect was overall small of the whole Indian nation.
