Music by Kevin MacLeod. Available under the Creative Commons Attribution 3.0 Unported license. Download link: https://incompetech.com/music/royalty-free/index.html?isrc=USUAN1100801

MacLeod's description:

Genre: Classical
Length: 4:22
Instruments: Viol, Drone

Based on 11th century sacred music, this piece can set you way way back in time almost instantly. Several faster and slower sections are available during this piece.
ISRC: US-UAN-11-00801
Calming, Mystical, Somber, Uplifting 2011