Every once in a while I grumble about the division of philosophy into "eras." I am one who errs on the side of regarding philosophers as contemporaries. I don't disregard history, "influence," "development," and so on, but I tend to believe Heidegger and Ockham and Plotinus and Sankhara would be able to understand each other (enough to have real arguments). Of course, this "understanding" must overcome all sorts of obstacles and can only occur now (unless there really is a Limbo somewhere, like Dante and Santayana envisioned, in which all these wise folk are forever discoursing) in the work of their descendants, i.e., you and me. This is one reason why scholarship remains pertinent to philosophy.
One of the worst symptoms of this chronological apartheid is the invention of the Dark Ages and other tremendous gaps in the standard histories. For the sake of the argument I'll just stay with the usual narrative that starts things up in Greece, because at least here we can say confidently that there is cultural continuity, whereas the influence of Chinese or Indian thinking on the west is more difficult to demonstrate. These standard accounts usually begin with Thales or someone, move fairly quickly to Socrates and Plato and Aristotle, then gloss over everyone till we get to St Paul with some hurried words about "schools" of Stoics and Epicureans and Skeptics. After Paul we again make haste to our quick date with St Augustine, after which, nodding to Boethius, we step into our time-machine and, mating our mixaphors, pole-vault over more than a millennium to Bacon and then Descartes. We may glance downward while in flight and see someone, usually St Thomas Aquinas, doing something-or-other and maybe William of Ockham shaking his head. Once on the ground again we go down the line, Rationalism (Descartes, Leibniz, Spinoza), Empiricism (Locke, Hume), Idealism (Berekley), the Transcendental move (Kant), and so on to Hegel and his various inversions (Marx, Kierkegaard, Nietzsche) and Frege before we split again into Continental (Husserl, Heidegger and so on via deconstruction) and Analytic (Russell, Wittgenstein, Quine and so on via modal logic).
I realize that my account of this travesty is itself a travesty. I know that a good teacher of history can convey a sense of how complex and tangled these chains are. I recognize that not all centuries are equally interesting to any other, and thus that there is some justification for compression. Moreover, to complain about gaps, especially in "survey" courses and the like, is to be a pedantic bore. You may thus skip if you wish the upcoming list, which is a partial enumeration of significant names of those left out of just one of the gaps. This is the one from about the 6th century to the 11th. I was inspired to make this list one day while reading John Deely's Four Ages of Understanding, where he writes that
The closest thing to a truly dark period in the so-called dark ages runs from the execution of Boethius in 524 down to the eleventh century work of Anselm, Abelard, and Peter Lombard. During this time what was left of ancient Roman educational structures in the western Empire crumbled to dust, and the nascent monastery and clerical schools took time to gestate a new educational blooming.Deely is one of the most scrupulous of scholars when it comes to attending to continuity of tradition, and I think he is right that beginning with Anselm we really can trace a more or less continuous conversation down to the present day. Continuity is only one of my interests, though. Looking at the stream of European philosophy/theology and its immediate tributaries, it's painfully clear that a great deal is omitted even from a history that attends to scholasticism, if it breaks off with Boethius and picks up with Anselm. (In the passage immediately following, Deely acknowledges three of these names (Ps.-Dionysus, Alcuin, and Erigena), and elsewhere makes use of Priscian.)
Pseudo-Dionysus (5th-6th c.)
Leontius of Byzantium (5th-6th c.)
Cassiodorus Senator (6th c.)
Gregory I ("the Great") (6th c)
Isidore of Seville (6th c.)
Priscian Caesariensis (6th c.)
Ildefonsus of Toledo (7th c.)
John Climacus (7th c.)
Isaac the Syrian (7th c.)
Stephen of Alexandria (7th c.)
Maximus Confessor (7th c.)
John Damascene (7th c.)
The Venerable Bede (7th-8th c.)
Alcuin of York (8th c.)
Simeon Kayyara (8th c.)
Photios of Constantinople (9th c.)
John Scotus Eriugena (9th c.)
Ishaq al-Kindi (9th c.)
David al-Mukkamas (9th-10th c.)
Zakariya al-Razi (10th c.)
Abu Nasr al-Farabi (10th c.)
Saadia Gaon (10th c.)
Muhammad ibn Hazm (10th c.)
Symeon the New Theologian (10th c.)
Anselm of Canterbury
Most of these figures are at least nominal Christians (quite a few are saints). A few are Islamic of Jewish thinkers (I have actually omitted a great number of figures, especially of the Jewish Savoraim and Geonim), but I take it as uncontroversial that their traditions fed into the main stream of the western philosophical tradition whose history is at issue here. I am leaving aside the other question of the legitimacy of the narrative that centers around "the [Christian] west". (This post was originally inspired by one by Tim Morton on al-Razi.) These names are of varying degrees of obscurity, but I take it that at least Maximus, Erigena, and al-Farabi ought to be common knowledge.
One of the issues that arises in considering a list like this is that many of the thinkers included are more typically considered jurists, scholars, grammarians, educators, and above all exegetes and theologians. The question arises then: to what extent is the invention of "the dark ages," at least in histories of western philosophy, a function of the (anachronistic?) separation of philosophy and religion? For even the tensions and polemics between these are are not, in the Middle Ages, framed in the same way as the modern distinction which puts them in separate university departments where they can safely ignore each other. To fight like al-Ghazali and ibn Rushd, you have to be up close and personal.