Union Territories & Panchayats
This Part doesn't apply to Scheduled Areas or tribal areas under Article 244, to Nagaland/Meghalaya/Mizoram, to Manipur's District Council hill areas, or (for district-level Panchayats) to Darjeeling's hill areas covered by the Darjeeling Gorkha Hill Council - and Article 243D's SC reservation doesn't apply to Arunachal Pradesh. However, a covered state's own Legislature can choose to extend this Part to itself by a special-majority resolution, and Parliament can extend it (with modifications) to Scheduled/tribal areas by ordinary law.
Certain tribal and hill areas of India have their own distinct traditional or specially-constituted self-government arrangements (often under the Sixth Schedule or similar local council laws), so this article carves them out of the standard Panchayati Raj framework rather than forcing a one-size-fits-all local government model onto areas with existing, different self-governance traditions.
This is why Nagaland, Meghalaya, and Mizoram - states with significant tribal populations and their own customary or specially-constituted local governance traditions - don't automatically get the standard Panchayat system this Part otherwise mandates nationwide.