It's one of ten background songs in the game.
Curiously, when the song is heard in-game, it stops at 2:21 and skips to the next track. However, if the player is currently in the Pause menu, it is heard in its entirety. It is unknown if this is caused by a bug, or if it is a deliberate easter egg.
Dune II: The Building of a Dynasty (AMI)
Dune II: The Building of a Dynasty (ARCH)
Dune II: The Building of a Dynasty (DOS)
Internal file names are DUNE5.XMI, DUNE5.C55, DUNE5.TAN, and DUNE5.PCS.
Internal file name is DUNE5.ADL.