Reddit reviews Byzantium: The Surprising Life of a Medieval Empire

Byzantium by Judith Herrin is extensive yet accessible. She is a professional archaeologist and an academic. The book is a rung on the ladder above pure popular history but is still readable if you have little background info on Byzantium. It is also a broad overview encompassing the entire span of the Empire.

I also recommend Lars Brownworth's 12 Byzantine Rulers podcast for a first contact with Byzantium. This is less academic and more popular history than Herrin's book, but is very well researched and also covers the entire span of Byzantine history from its Roman roots to its fall.

This is an entirely appropriate subreddit! Let nobody discourage you from asking for sources here.

There are AskHistorians book lists. The Europe mentions Byzantine books in two sections, so you might be best served by doing a search for "Byz" (Well, three sections, except that one section mentions only Herrin, J. Byzantium: The Surprising Life of a Medieval Empire, which I assume is the Herrin book you were referring to.)

AskHistorians has a podcast. Episodes 20 and 21 are "Byzantines: Macedonian and Komnenian Dynasties".

The Constitutio Antoniniana which granted Roman citizenship to all free inhabitants of the empire was issued in 212 AD and there is quite a lot of Roman history after that. Soon follows the so called “crisis of the 3rd century” between 235 and 284 AD throughout which the empire was shaken by internal as well as external problems. Next comes Late Antiquity, a period which has attracted a lot of scholarly attention in recent decades. It saw some huge changes like Christianity’s rise to dominance or the final partition of the empire into a western and eastern half that you mentioned. And while the western part already disappeared throughout the 5th century the Eastern Roman Empire would survive for a long time further. The rise of the first Islamic caliphate in the 7th century AD cost it much of its territory and caused further transformations. This surviving remnant of the Roman Empire, now centred around Constantinople, is usually called the Byzantine Empire. Its eventful history would continue through the entire Middle Ages until 1453 AD when it was finally conquered by the Ottomans. So all in all there is more than a millennium of further Roman history to cover.

• Michael Kulikowski, The Triumph of Empire. The Roman World from Hadrian to Constantine (2016) might be a good point to start as it begins right in the period you’re already familiar with and leads you through the 3rd century crisis to the beginning of Late Antiquity.
  
  
• Peter Brown, The World of Late Antiquity. AD 150-750 (1989) is pretty much the foundational text for the modern scholarship on the named period. Its short, richly illustrated and just all around fantastic.
  
  
• Peter Heather, The Fall of the Roman Empire. A new history of Rome and the Barbarians (2007) covers the developments that would lead to the end of the Western Roman Empire.
  
  
• Peter Sarris, Empires of Faith. The Fall of Rome to the Rise of Islam. 500-700 (2011) has a larger focus than just Roman history and also concerns itself with the post Roman kingdoms in the west as well as (like the title says) the rise of Islam.
  
  
• Judith Herrin, Byzantium. The surprising life of a Medieval Empire (2009) is probably one of the best ways to first familiarise yourself with the huge timespan that is Byzantine history.
  
  
• Averil Cameron, The Byzantines (2006) is another excellent introduction to the entirety of Byzantine history.
  
  There are quite a lot of books that go into further detail about the different periods of Byzantine history but for the start those two general introductions should probably suffice. Of course you can always ask for more. I hope this helps!

Judith Herrin's Byzantium: the Surprising Life of a Medieval Empire is probably the most accessible one I've read. It's fun enough that I'd recommend it to someone who doesn't study history academically, but it's not just airport bookstore fare either.

I can recommend Judith Herrin's very readable Byzantium - The Surprising Life of a Medieval Empire.