Isn't there an old Roman ethic that historians should stick to res publica or something like that?
Plutarch - Parallel Lives. First Century. Greece of late antiquity during the Pax Romana. The height of the power of the Roman empire. Plutarch is wiki'd as a biographer (Britannica as well) rather than a historian. Originally written in Koine Greek.
Dio Cassius - The Roman History: The Reign of Augustus. Originally written in Latin.
Peter Brown - the World of Late Antiquity. I didn't know about this one until I wiki'd late antiquity not knowing exactly what it referred to. He is a modern historian exploring what we call the Dark Ages. Originally in English.
Eric H Cline - 1177 BC the year civilization collapsed - an exclamation point to the end of Mycenean Greece. I didn't think we'd ever know exactly when it came to an end, but why not? That would be the end of what most people consider the ancient world. Originally in English.
Procopius - The Secret History The story of Justinian's reign. Originally in Koine Greek.
Ian Wood - the Merovingian Kings - covers neither Clovis I nor Charlemagne, so it's not that interesting. It's really missing Merovich, Childeric I, Clovis I, the book as is, Charlemagne, Louis the Pious, and his 3 sons. That puts the timeline from the namesake of the line through the end of the Carolingian Empire, in 816, as seen by the Catholic church. Originally in English
Geoffrey of Monmouth - The History of the Kings of Britain - AFAIK this is the original story of king Arthur included. Written in the 12th century, in Welsh. It appears he is an Angle? He is fighting the Saxons in Britain. There's no Excalibur or anything really exciting.
As an added bonus, I'd like to provide the definition of history from the Encyclopedia Britannica:
History, the discipline that studies the chronological record of events (as affecting a nation or people), based on a critical examination of source materials and usually presenting an explanation of their causes.