Complex sentence: The political sovereignty of the Sultanate was dissolved in 1917 but the traditional, cultural and proprietary sovereignty remain to the descendants of the royal family are still "de facto" recognized and honored as royalty in Sulu.
Split into simpler sentences: The political sovereignty of the Sultanate was dissolved in 1917. The traditional, cultural and proprietary authority remain; the descendants of the royal family are still "de facto" recognized and honored as royalty in Sulu.