Originally Posted by Moros
But the 'classical' historian was only interested in political history as it impinged on the Greek or Roman empires. There was a change in focus, but where is the indication that the method and style altered?
There was a change in focus when the Roman Empire became Christian in the 4th century. The 'classical historians' when writing political history thereafter had to ask themselves what method and style they would use when dealing with the Christian religion and the Christian Emperor. Ammianus stays well clear of the "plain and simple religion of the Christians".
OTOH Zosimus, according to WIKI "The historian's object was to account for the decline of the Roman Empire
from the polytheistic point of view. Zosimus is the only non-Christian source for much of what he reports.
Zosimus does not favour Constantine. The obituary Ammianus wrote for Constantine is missing. We can only guess what it might have reported. He certainly did not favour Constantius. Julian does not favour Constantine, or his sons.
The church historians OTOH glorify the "Thrice Blessed" Constantine.
I find these two diametrically opposed reports fascinating.
Who do we believe? The academic paradigm, closely associated with the inside "specialists" in ecclesiastical history, has traditionally followed the histories of the church on key elements, where they diverge from Zosimus' and Julian's invectives against Constantine.
Perhaps you could consult Eunapius or Olympiodorus or Festus or Eutropius or Aurelius Victor. After them, look to Zosimus, Priscus, Malchus, pseudo-Joshua, Procopius, Jordanes, Gregory of Tours, Agathias, Menander, Theophylact Simocatta, etc, etc. These authors focused on the political history of their times or earlier. So well into the 7th Century, the classical 'style' survived (if you think style = subject matter).
Thanks for the useful list. I have spent some time looking at these and others and have copied a summary and brief detail list below.
My original comment about a decline in "political reporting" was reserved for the 4th century, specifically between 312-353 CE. Aside from some brief reports from the pagans, the epoch prior to the commencement of Ammianus' history appears to me to be represented exclusively by ecclesiastical histories.
These (4) Christian sources passed over the political history of the reception of the Bible and the Christian State in the Roman Empire. I have not included these ecclesiastical historians (Eusebius, Socrates, Sozomenus and Theodoretus) in the following.
Historians of the 4th-7th centuries
**** 4th century
Praxagoras of Athens (fl. early fourth century)
Festus (fl. 4th century CE)
Eutropius (fl. later 4th century CE)
Sextus Aurelius Victor (c. 320 – c. 390 CE)
Eutropius (fl. later fourth century)
Ammianus Marcellinus (c. 325–330 died c. 391–400)
**** 5th century
Eunapius (fl. 4th–5th century)
Olympiodorus ( fl.c. 412–425 CE)
Zosimus (fl. 490s–510s CE)
Priscus (fl. 5th century CE)
Malchus (fl. 5th century CE)
**** 6th century
pseudo-Joshua (fl. 6th century)
Procopius (c. 500 – c. 554 CE)
Jordanes (fl. 6th century)
Gregory of Tours (c.538 – 594 CE)
Agathias (530 – 582/594 CE)
Menander (fl. 6th century)
**** 7th century
Theophylact Simocatta (fl. 7th century)
**** 4th century
Praxagoras of Athens (fl. early fourth century) https://en.wikipedia.org/wiki/Praxagoras_of_Athens
wrote three historical works, which are all lost: a history of the Kings of Athens,
a history of Alexander the Great, and a panegyric biography of the emperor Constantine.
A few fragments of the biography of Constantine are preserved in the Bibliotheca of Photius (cod. 62).
Festus (fl. 4th century CE) https://en.wikipedia.org/wiki/Festus_(historian
also known as Rufus Festus, Ruffus Festus, Sextus Festus, Sextus Rufus, and Sextus, was a Late Roman historian and proconsul of Africa whose epitome Breviarium rerum gestarum populi Romani ("Summary of the history of Rome") was commissioned by the emperor Valens in preparation for his war against Persia. It was completed about AD 379. The Breviarium covers the entire history of the Roman state from the foundation of the City until AD 369. The book consists of 30 small parts treating events in Roman history in terse overview, mainly focused on military and political conflicts. It is estimated as a work of very low quality
Eutropius (fl. later 4th century CE) https://en.wikipedia.org/wiki/Eutropius_(historian
held the office of secretary (magister memoriae) at Constantinople, accompanied the Emperor Julian (361–363) on his expedition against the Persians (363), and was alive during the reign of Valens (364–378), to whom he dedicates his Breviarium historiae Romanae and where his history ends. The Breviarium historiae Romanae is a complete compendium, in ten books, of Roman history from the foundation of the city to the accession of Valens. It was compiled with considerable care from the best accessible authorities, and is written generally with impartiality, and in a clear and simple style. Although the Latin in some instances differs from that of the purest models, the work was for a long time a favorite elementary school-book. Its independent value is small, but it sometimes fills a gap left by the more authoritative records
Sextus Aurelius Victor (c. 320 – c. 390 CE) https://en.wikipedia.org/wiki/Aurelius_Victor
De Caesaribus - from Augustus to Constantius II. The work was published in 361.
Eutropius (fl. later fourth century) https://en.wikipedia.org/wiki/Eutropius_(historian
Breviarium historiae Romanae - a complete compendium, in ten books,
of Roman history from the foundation of Rome to the accession of Valens.
Sulpicius Alexander (fl. late fourth century) https://en.wikipedia.org/wiki/Sulpicius_Alexander
Roman historian of Germanic tribes. His work is lost, but quoted by Gregory of Tours.
It was perhaps a continuation of the Res gestae by Ammianus Marcellinus (which ended in 378 AD)
and dealt with events at least until the death of Valentinian II (392 AD).
Ammianus Marcellinus (c. 325–330 died c. 391–400) https://en.wikipedia.org/wiki/Ammianus_Marcellinus
Wrote the penultimate major historical account surviving from Antiquity (preceding Procopius). His work, known as the Res Gestae, chronicled in Latin the history of Rome from the accession of the emperor Nerva in 96 to the death of Valens at the Battle of Adrianople in 378, although only the sections covering the period 353–378 survive.
**** 5th century
Eunapius (fl. 4th–5th century) https://en.wikipedia.org/wiki/Eunapius
Greek sophist/historian - principal surviving work
is "the Lives of Philosophers and Sophists"
Olympiodorus ( fl.c. 412–425 CE) https://en.wikipedia.org/wiki/Olympiodorus_of_Thebes
an historical writer of classical education, a "poet by profession" as he says of himself, who was born at Thebes in Egypt, and was sent on a mission to the Huns on the Black Sea by Emperor Honorius about 412, and later lived at the court of Theodosius II, to whom his History was dedicated. The record of his diplomatic mission survives in a fragment among the forty-six in the epitome by the patriarch Photius, who considered Olympiodorus a "pagan", doubtless for his classical education. An author of a history in twenty-two books of the Western Empire from 407 to 425, which was used by Zosimus and Sozomen and probably Philostorgius, as J.F. Matthews has demonstrated. The original is lost, but an abstract is given by Photius.
Zosimus (fl. 490s–510s CE) https://en.wikipedia.org/wiki/Zosimus
Zosimus' Historia Nova (Ἱστορία Νέα, "New History") is written in Greek in six books. For the period from 238 to 270, he apparently uses Dexippus; for the period from 270 to 404, Eunapius; and after 407, Olympiodorus... The historian's object was to account for the decline of the Roman Empire from the polytheistic point of view. Zosimus is the only non-Christian source for much of what he reports. There are no doubt numerous errors of judgment to be found in the work, and sometimes (especially in the case of Constantine) an intemperate expression of opinion, which somewhat exaggerates, if it does not distort the truth. It is not to be wondered at that one who held to the old faith should attribute the downfall of the Roman Empire in great part to the religious innovations attendant upon the spread of Christianity.
Priscus (fl. 5th century CE) https://en.wikipedia.org/wiki/Priscus
Priscus was the author of an eight-volume historical work, written in Greek, entitled the History of Byzantium (Greek: Ἱστορία Βυζαντιακή), which was probably not the original title name. The History probably covered the period from the accession of Attila the Hun to the accession of Emperor Zeno (r. 474–475), or from 433 up until 474 AD. Priscus's work currently survives in fragments and was very influential in the Byzantine Empire. The History was used in the Excerpta de Legationibus of Emperor Constantine VII Porphyrogenitus (r. 913–959), as well as by authors such as Evagrius Scholasticus, Cassiodorus, Jordanes, and the author of the Souda. Priscus's writing style is straightforward and his work is regarded as a reliable contemporary account of Attila the Hun, his court, and the reception of the Roman ambassadors. He is considered a "classicizing" historian to the extent that his work, though written during the Christian era, is almost completely secular and relies on a style and word-choice that are part of an historiographical tradition dating back to the fifth century BC
Malchus (fl. 5th century CE) https://en.wikipedia.org/wiki/Malchus_(historian
According to Suda, he wrote a history extending from the reign of Constantine I to that of Anastasius I; but the work in seven books, of which Photius has given an account (Bibl. cod. 78), and to which he gives the title Βυζαντιακά, comprehended only the period from the final sickness of the Eastern emperor Leo I (473 or 474), to the death of Julius Nepos, emperor of the West (480). It has been supposed that this was an extract from the work mentioned by Suidas, or a mutilated copy: that it was incomplete is said by Photius himself, who says that the start of the first of the seven books showed that the author had already written some previous parts, and that the close of the seventh book showed his intention of carrying it further, if his life was spared. Photius praises the style of Malchus as a model of historical composition; pure, free from redundancy and consisting of well-selected words and phrases. He notices also his eminence as a rhetorician, and says that he was favourable to Christianity; a statement which has been thought inconsistent with the praises for Pamprepius. The works of Malchus are lost, except the portions contained in the Excerpta of Constantine VII, and some extracts in Suda.
**** 6th century
pseudo-Joshua (fl. 6th century) https://en.wikipedia.org/wiki/Joshua_the_Stylite
The Chronicle of Pseudo-Joshua the Stylite - Syriac text written, in all probability, by an inhabitant of Edessa almost immediately after the conclusion of the war between Rome and Persia in 502 6506 AD. Although that conflict is treated in other ancient texts, none of them can match "Joshua" in his wealth of detail, his familiarity with the region where the hostilities occurred, and his proximity in time to the events. The Chronicle also vividly describes the famine and plague that swept through Edessa in the years immediately before the war. The work is a document of great importance for both the social and military history of late antiquity, remarkable for the information it provides on Roman and Persian empires alike.
Procopius (c. 500 – c. 554 CE) https://en.wikipedia.org/wiki/Procopius
Procopius of Caesarea (Greek: Προκόπιος ὁ Καισαρεύς, Latin: Procopius Caesariensis; c. 500 – c. 554 AD) was a prominent late antique scholar from Palaestina Prima. Accompanying the Roman general Belisarius in the wars of the Emperor Justinian, he became the principal historian of the 6th century, writing the Wars (or Histories), the Buildings of Justinian and the celebrated (and infamous) Secret History. He is commonly held to be the last major historian of the ancient Western world.
Jordanes (fl. 6th century) https://en.wikipedia.org/wiki/Jordanes
6th-century Roman bureaucrat, who turned his hand to history later in life. While he also wrote Romana about the history of Rome, his best-known work is his Getica, written in Constantinople  about AD 551. It is the only extant ancient work dealing with the early history of the Goths.
Gregory of Tours (c.538 – 594 CE) https://en.wikipedia.org/wiki/Gregory_of_Tours
Saint Gregory of Tours (30 November c. 538 – 17 November 594) was a Gallo-Roman historian and Bishop of Tours, which made him a leading prelate of Gaul. He was born Georgius Florentius, later adding the name Gregorius in honour of his maternal great-grandfather. He is the main contemporary source for Merovingian history. His most notable work was his Decem Libri Historiarum or Ten Books of Histories, better known as the Historia Francorum ("History of the Franks"), a title given to it by later chroniclers, but he is also known for his accounts of the miracles of saints, especially four books of the miracles of Martin of Tours. St Martin's tomb was a major draw in the 6th century, and Gregory's writings had the practical aspect of promoting this highly organized devotion.
Agathias (530 – 582/594 CE) https://en.wikipedia.org/wiki/Agathias
This work in five books, On the Reign of Justinian, continues the history of Procopius, whose style it imitates, and is the chief authority for the period 552–558. It deals chiefly with the struggles of the Imperial army, under the command of general Narses, against the Goths, Vandals, Franks and Persians
Menander (fl. 6th century) https://en.wikipedia.org/wiki/Menander_Protector
continued the history of Agathias, covering the period from 558 to 582. Menander took as his model Agathias who like him had been a jurist, and his history begins at the point where Agathias leaves off. It embraces the period from the arrival of the Kutrigurs in Thrace during the reign of Justinian in 558 down to the death of the emperor Tiberius in 582. Considerable fragments of the work are preserved in the Excerpts of Constantine Porphyrogenitus and in the Suda. Although the style is sometimes bombastic, he is considered trustworthy and is one of the most valuable authorities for the history of the 6th century, especially on geographical and ethnographical matters. Menander was an eye-witness of some of the events he describes. Like Agathias, he wrote epigrams
**** 7th century
Theophylact Simocatta (fl. 7th century) https://en.wikipedia.org/wiki/Theophylact_Simocatta
Byzantine historiographer, arguably ranking as the last historian of Late Antiquity, writing in the time of Heraclius (c. 630) about the late Emperor Maurice (582–602). history in eight books, for which period he is the best and oldest authority.