Not medieval, but nice. :)
Although this is a rather long song, I tried to listen to as much as I could and I can tell you from experience that this is not at all medieval, although it would be very fitting in a game made about that era (a common misconception due to the use of orchestral/cinematic music in games). Reasons why include the use of seventh chords, instruments not available at that time, and the use of varying tempos and melodies, especially counter-melodies (music until the early middle ages was so simple in comparison to contemporary pieces that it generally didn't even have chords, but only one melody!).
I thoroughly enjoyed the use of percussion. You did a nice job accenting the piece and the various themes. Most of all, you have a great mind for coming up with moods that flow nicely through various feels.
For your credit, some parts remind me of the soundtrack for Age of Empires I and II.
There's so much material, I can't give too much constructive feedback without killing myself, but you need to look at your transitions between themes and see how you can 'lead' and 'hint' at new themes right before they come in so they aren't so abrupt, especially the string part at the end when the other melody just... stops. At the beginning, at 0:17 when the melody changes, consider having a flute or other instrument play the first melody like a Round, which is accurate to the Middle Ages coincidentally. Also, you don't make much use of cymbals or gong crashes, which can help separate themes. In addition, I didn't hear much in terms of timpani rolls, which are greatly helpful if you keep them PP to mP and in the background for making a nice dark overlay. Don't be afraid to consider using more than just trombone/brass for the theme starting at 1:27, having a trumpet play the melodies' higher extremities might be nice, and some form of counter melody (although the timpani is very nice). The transition after that phase is clean, thanks to the wideness of the final chord.
You did a nice job on this, don't be too modest. I may look over some more of your stuff in the future if I have time.
Keep it up!