माना जाता है कि गौतम (सिद्धार्थ) ने अंतिम ज्ञान प्राप्ति के लिए बोधगया जाने से पहले छह साल तक किस स्थान पर पवित्र ध्यान लगाया था?

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?