Esther 1:1

"This is what happened during the time of Xerxes, the Xerxes who ruled over 127 provinces stretching from India to Cush." NIV translation

We see here that this book is a historical record of actual events that can be verified. We also see that the Persian empire was quite huge as it stretched from India to Ethiopia.

Esther 1:2 - 4

"At that time King Xerxes reigned from his royal throne in the citadel of Susa, and in the third year of his reign he gave a banquet for all his nobles and officials. The military leaders of Persia and Media, the princes, and the nobles of the provinces were present. For a full 180 days he displayed the vast wealth of his kingdom and the splendor and glory of his majesty." NIV translation

The king threw a massive party and anyone who was anyone was there. This banquet was held to get support for the king's plans to attack Greece and expand his kingdom. This party was a way to show the people that the kingdom had the money to pay for the planned war. The party lasted for a full six months in which the king tried to show how great he was.