The Indian Evidence Act, 1872
§113 — Proof of cession of territory
– A notification in the Gazette of India that any portion of British territory has [before the commencement of Part III of the Government of India Act, 1935 (26 Geo. 5, c. 2)] been ceded to any Native State, Prince or Ruler, shall be conclusive proof that a valid cession of such territory took place at the date mentioned in such notification.