Masters & Minions: The StarCorps Dossiers states on page that Alshain was a major Principality world in the Kingdom of Rasalhague before it was a District capital in the Draconis Combine. However, Alshain doesn't show up on the map of the Inner Sphere as at 2596 on page 159 of Historical: Reunification War, or on the map on page 25 of Handbook: House Steiner, which shows the region of space Alshain would be in as at 2571.
Is Masters & Minions correct? If it is, what caused Alshain to drop off the maps in the Age of War or earlier?