https://indianexpress-com.cdn.ampproject.org/v/s/indianexpress.com/article/technology/science/researchers-finally-cracked-why-the-indus-valley-civilisation-collapsed-10391600/lite/?amp_gsa=1&_js_v=a9&usqp=mq331AQGsAEggAID#amp_tf=From%20%251%24s&aoh=17644424592628&csi=0&referrer=https%3A%2F%2Fwww.google.com&share=https%3A%2F%2Findianexpress.com%2Farticle%2Ftechnology%2Fscience%2Fresearchers-finally-cracked-why-the-indus-valley-civilisation-collapsed-10391600%2F
A possible explanation
People forget just how dependent agriculture (and therefore their survival) is on water
Huge effect and often overlooked from discussions
One can just imagine how people simply gave up and moved away once they were unable to flush their toilets...
:-\
Or wash their chariots on a Sunday