Complex sentence: Before the Unification of Nepal, Khanchi, was one of the 24 principalities in the Gandaki River Basin was annexed by Gorkha in the year 1786 AD (1843 BS).
Split into simpler sentences: Before the Unification of Nepal, Khanchi, was one of the 24 principalities in the Gandaki River Basin. Khanchi was annexed by Gorkha in the year 1786 AD (1843 BS).