प्राचीन भारतीय परम्परा में प्रथम विधि निर्माता (प्रथम कानून निर्माता) किसे माना जाता 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?