Lars Brownworth has a nice lecture series on Byzantine history available as a podcast. In some ways, this can qualify as lost history, because few in the West know much about the Byzantine Empire. They had a pretty good run. If you go from the fall of Rome, it was another 1000 years before Byzantium was finally overrun by the Turks.
There are a lot of interesting threads here. Byzantium is partially neglected because of the Great Schism in 1054, when Eastern and Western Christianity sundered their communion. Also there is an element of cultural strangeness for us Westerners, because Byzantium took a very different cultural course than Europe. The history of Byzantium is also tied up in the history of the Crusades, and of the rise of Islam.
Even the Mongols get into the act, coming in from the East to harry the Abbasid dynasty in Baghdad. Actually, harry is too gentle a word. In 1258 Baghdad was obliterated by the Mongols, and the Abbasid Caliph killed. After this, the Middle East became a much rougher place, because the dynasties that arose to replace the Abbasids were less pleasant. This may also be the source of the legend of Prester John, the Eastern Christian king who it was hoped would help conquer Islam. A sizable minority of the Mongol Empire was Christian, and emissaries were sent back and forth to Europe regularly.
This lecture series is an easy introduction to this part of world history.