This was the age when Christianity took hold; its midpoint 350 is close to the date when it became the state religion of the Roman empire.
Zhang Heng (78 - 139) Chinese astronomer.
Claudius Ptolemy & & (c.85 - 165). made astronomical observations 127-141, compiled and systematised the knowledge of his day: Harmonics on music, Optics on light, including angles of refraction for several media, Geographia including map projections, Tetrabiblos on astrology, Planetary Hypothesis on cosmology, Syntaxis or 'Almagest' on astronomy.
Lucius Apuleius (c.120 - 180), satirical author of The Golden Ass & and the Apology a speech in defence of a slander against him.
Marcus Aurelius & & & & & (121 - 180) Roman consul (140) and emperor (161), stoic philosopher Meditations & & 167.
Galen, aka Claudius Galenus of Pergamum & & & & & (c.130 - c.201), physician to gladiators and emperors, including Marcus Aurelius, 83 treatises extant including On the Natural Faculties, Exhortation to Study the Arts, Diagnosis in Dreams and 15 commentaries on Hippocrates.
The Nine Chapters c.210, a Chinese mathematical work.
Diophantus (fl.3rd century) Alexandrian mathematician, Arithmetica introduced 'diophantine equations' in theory of numbers.
Aurelian (212 - 275), Roman emperor 270. Defeated Zenobia of Palmyra (who had conquered Egypt 269 and most of Asia Minor).
Diogenes Laertius, biographer of the Greek philosophers.
Diocletian (245 - 313), Roman emperor 284-305.
Arius (250 - 336), theologian.
Eusebius of Caesaria (c.264 - 340), theologian, Ecclesiastical History 324, not averse to 'pious forgery'.
Constantine I (274 - 337), Roman emperor 323, made christianity the state religion 324, adopted Nicene creed 325, made Constantinople (Byzantium) the capital 330.
Athanasius (296 - 373), theologian.
Ambrose (339 - 397) bishop of Milan 374, introduced hymns, ritual and chant.
Jerome, aka Eusebius Sophronius Hieronymus (c.342 - 420), Vulgate bible in Latin 386.
Theodosius I (c.346 - 395), Roman emperor 379.
Augustine of Hippo & & & & & (354 - 430) - christian 'neoplatonist' philosopher and theologian.
Pelagius, aka Morgan (c.360 - c.420), theologian, rejected the doctrines of original sin and predestination.
Alaric I (370 - 410) king of the Visigoths 395, sacked Rome 410.
Hypatia (c.375 - 415), Alexandrian philosopher, murdered by a christian mob, encouraged by archbishop Cyril of Alexandria (376 - 444) who also expelled the Jews, and persecuted Nestorius, patriarch of Constantinople 428 - 431 (d.451), for heresy.
Attila (c.406 - 453) king of the Huns 434.
Proclus (411 - 485).
Patrick (5th century), missionary of christianity to Ireland 432.
450 Tsu Ch'ung-Chih and Tsu K^eng-Chih compute pi to six decimal places
Aryabhata the Elder (476 - 550) Aryabhatiya & Indian mathematician and astronomer, uses Sanskrit syllabic numeration.
550 Hindu mathematicians give zero a numeral representation in a positional notation system
Columba, aka Colm (521 - 597 Iona), missionary of christianity in Scotland.
David, aka Dewi, (d.601), Welsh bishop, patron saint of Wales.
Augustine of Canterbury (d.604), missionary of christianity in England, first archbishop of Canterbury.
Gregory I 'the Great' (c.540 - 604) Pope 590, systematization of ritual and chants.