Most of Asimov's non-fiction was aimed at the masses (as was Sagan's Cosmos), so they tend not to go into great depth. However he was excellent at showing how an event or discovery would have direct or indirect impact on a future event or discovery (standing on the shoulders of giants and all that). Most of these were written in the 1960's and 1970's
I have always enjoyed Isaac Asimov's non-fiction. He wrote numerous history books, including the excellent
Asimov's Chronology of the World: The History of the World From the Big Bang to Modern Times.
The Near East: 10,000 Years of History
The Land of Canaan
The Egyptians
The Greeks: A Great Adventure
The Roman Republic
The Roman Empire
Constantinople: The Forgotten Empire
The Shaping of England
The Shaping of France
The Dark Ages
Christopher Columbus: Navigator to the New World
Ferdinand Magellan: Opening the Door to World Exploration
The Shaping of North America
The Birth of the United States
Asimov also wrote excellent histories of science and mathematics:
Asimov's Biographical Encyclopedia of Science and Technology
Asimov's Chronology of Science and Discovery
A Short History of Biology
A Short History of Chemistry
Most of Asimov's non-fiction was aimed at the masses (as was Sagan's Cosmos), so they tend not to go into great depth. However he was excellent at showing how an event or discovery would have direct or indirect impact on a future event or discovery (standing on the shoulders of giants and all that). Most of these were written in the 1960's and 1970's
I've searched for books on Parthia many times but I can't seem to find anything ever. I did find this just now though:
http://www.amazon.com/gp/aw/d/0395065771/ref=mp_s_a_1_1?qid=1369132329&sr=8-1&pi=SL75