निम्नलिखित प्राचीन महाजनपदों में से कौन सा वर्तमान उत्तर प्रदेश के क्षेत्र में स्थित नहीं 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?