कनिष्क के सारनाथ बौद्ध प्रतिमा अभिलेख में किस वर्ष या तिथि का उल्लेख मिलता 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?