गैरिक मृदभांड संस्कृति (OCP) तथा कृष्ण-लोहित मृदभांड संस्कृति (BRW) मुख्य रूप से किस पुरातात्विक काल से संबंधित हैं?

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?