Cyrus the Great was the founder of the Achaemenid Empire, located in Western Asia, and considered to be the very first Persian Empire. The Empire was founded in 550 B.C. and lasted for over two hundred years, and was larger than any previous empire in history, at its peak spanning five and a half million square kilometers. It was noted mainly for its incredible administrative machine and the way in which its infrastructure was centralized through one government, despite the size of the Empire.
The Cyropaedia is a fictionalized version of Cyrus' biography, and was written in 370 B.C. by Xenophon of Athens. Xenephon studied under Socrates, and was respected as both a gentleman and a soldier. The book was extremely influential; it was used by many Medieval writers as the literary road-map for a genre of writing called Mirrors for Princes, books that were used as instructional manuals for future rulers and royals, guiding them in both what to do, and what to avoid.
At its heart, the Cyropaedia is the biography of an idealized version of a ruler. He is benevolent and kind, yet courageous and unflinching in the face of danger. He is a despot, but never abuses his despotic power. Because of this romanticizing the book is difficult to classify because it is not really a history book, due to the questionable validity of the stories it tells. As a history of a region, and of an Empire, it is probably best to be taken with a pinch of salt, but it is useful in terms of the biographical details it gives of Cyrus the Great himself. Because he is depicted as the ideal ruler, and the example of the way in which a government should preside over its citizens, there has to be some grain of truth in the depiction, because otherwise, an alternative picture of the real Cyrus the Great would have emerged to counter Xenophon's romanticized one.
Could Xenephon have experienced Cyrus the Great for himself? Well, not personally, but Cyrus' rule was recent enough in Xenephon's lifetime to be accurately remembered and recounted word of mouth by his fellow citizens. Xenephon spent some time in Persia with an army of Greek mercenaries employed by Cyrus the Younger, and would have heard many tales recounted of the upstart's ancestry. These tales most likely form a truthful and accurate outline of Cyrus the Great and his rule, inside which Xenephon painted a more elaborate and detailed picture from his imagination.
Xenephon is one of the most widely respected philosophers of both his day, and of the realm of philosophy as a whole. Both Julius Cesar and Alexander the Great were known to carry a copy of the Cyropaedia with them, but the book was largely fogotten about after the classical civilizations had disappeared, until the Middle Ages, when it became important again during the Renaissance period.
Xenophon is believed to have been a vehement opponent of democracy, preferring oligarchy, or at least despotism, over a democratic, Socratic state of affairs in a nation. This is evident in the Cyropaedia as he describes a despotic leader who is nonetheless kind and benevolent, clearly caring deeply for both the welfare of his people and the prosperity of his Empire.