It also of tends to decide how many people will drown as the amount of rain as you say is quite variable.
As for the Veddic period it depends on what you call weapons. A lot of early weapons can, in some cultures, be nearly indistinguishable from any other hand tools. What is known with certainty is that by the Time of Alexander the Great, the military of the various states of Northern India was more than sufficient to fight that same Alexander to a stand still something no other contemparay even came close to.
Annoy a leftist: Think logically.