सिंधु सभ्यता में खोपड़ी की शल्य चिकित्सा का साक्ष्य कहाँ से प्राप्त हुआ 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?