Very nice posts by both of you. When I was first learning about the Indus Vally culture in the 1950's, the primary conjecture for the demise was deforestation because of the need for firewood. The people would have had to move to places with trees, and the area would have become desertified. Which came first, the chicken or the egg?
I used to tell this to a teacher of mine, back in school, 'If the egg came first, who incubated it???'.
LoL!
I've read that an earthquake or two probably caused the now-dried Saraswati river to either change course, or disappear completely. What of that theory?
I must say, as an Indian, the Indian education system stresses very little on the Indus Valley Civilisation. The history of the country may be tiringly long, but this area gets a fraction of the attention it really deserves.