ऋग्वेद में, खेती की जाने वाली भूमि के बीच बंजर या बिना जोती गई भूमि की पट्टी को क्या कहा जाता 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?