The subject "The Union and its territory" is given in Part-I of the Indian Constitution.
It is given between Articles 1-4 of the constitution.
Part - I contains the law of establishment, renaming, merging, or changing the borders of the Indian states.
Article 1 of the constitution says that India, that is Bharat, a union of states and territory.
On 5 August 2019, the government revoked Article 370 which gave special status to Jammu and Kashmir, and proposed that the state be bifurcated into two union territories, Jammu and Kashmir and Laddakh. They are now two new union territory of India.