Below is a list of philosophical and theological writings from the Early Middle Ages!
Lactantius (250 - 325)
Institutiones Divinae
St. Athanasius (296/298 - 373)
Life of Anthony
On The Incarnation
Hilary of Poitiers (310 - 367)
The Trinity
Epiphanius of Salamis (310/320 - 403)
The Panarion of Epiphanius of Salamis
St. Jerome (342/347 - 420)
Letters
St. Augustine (354 - 430)
City of God
Confessions
On Christian Doctrine
On Free Choice of the Will
On the Trinity
St. Ambrose (374 - 397)
Hexameron
On The Duties
On The Holy Spirit
On The Mysteries
Theodoret (393 - 458)
Commentaries
Stobaeus (5th Century)
Anthology
Simplicius of Cilicia (480 - 540)
On Aristotle