सिंधु घाटी सभ्यता से जुड़ा एक महत्वपूर्ण पुरातात्विक स्थल, मांडा किस नदी के तट पर स्थित है?

In Ancient Indian Statecraft, Kautilya's 'Rajamandala' theory primarily deals with:

The First Buddhist Council was held at ______.

Which ancient Indian text contains references indicating that population counts or census-like records were maintained in ancient India?