Expanding even more to those points. The Persians being a nomadic people in the 7th century BC did not have writing. By the time of Cyrus the Great the Persians had adopted cuneiform and recorded their history on tablets or cylinders or the occasional wall inscription. None of these have survived with more or less the exception of the so called Cyrus Cylinder (which is actually a Babylonian record) and parts of the Behistun Inscription and the Naqsh e Rustam inscription. Much is the case with the Sassanid Dynasty, we only have a few odd inscriptions here and there. The Parthians suffer from two problems, that their state was established by nomadic tribes and also that they relied on Greeks and Persians to do the actual administration of the empire. So where as Greek was the lingua franca of the Arsacid dynasty the Persians actually had no reason to preserve Parthian history. As such a lot of Sassanid era history was recorded by the Romans though a great deal of it only touches on the subject of the Sassanian wars waged in Syria and Mesopotamia. Ironically we are somewhat fortunate for these wars because it gave the local Syrians to record their own history of these events. Although there is actually an overwhelming amount of history recorded by multiple sources in this period, so much so that a lot of the texts actually contradict as to what actually happened during these Sassanian wars. Interest in this subject persisted into the 400's and the 500's and there were even Byzantine histories that talk of these wars, histories written in the 1000's and 1100's.
@San Felipe, If you want some different history feel free to check out what I've been working on here, a history of Oda Nobunaga, or at least the early part. It is essentially biographical while also looking at the political and military history of the period. So far I've written two parts and am working on the third, eventually I will also get the fourth part out. Actually my real goal is to publish a book on the subject, maybe a bit a early for me to admit this. Though all of the hype surrounding the release of the new Total War title has kind of made me want to write something about the Three Kingdoms.
http://www.twcenter.net/forums/showt...-Rise-to-Power