Complex sentence: Seats were reserved in the then state Assembly for all three communities, which implies that all three communities of Sikkim viz.Bhuria, Lepcha or Nepali were equally treated as Tribals by them.
Split into simpler sentences: Seats were reserved in the then state Assembly for all three communities, which implies that all three communities of Sikkim viz. Bhutia, Lepcha or Nepali were equally treated as Tribal by them.