The Assam (Alteration of Boundaries) Act, 1951 was enacted on September 1, 1951.The State of Assam is situated at the north-eastern part of India. The Assam State totally consists of an area of 30,285 miles. The neighboring countries of India like Bangladesh and Bhutan has its international borders with the State of Assam. The Indo-Bhutan Treaty of Friendship entered on August 8, 1949 and confirmed thereafter was the main reason behind such transfer. According to Article 4 of the said treaty, the Indian Government took an undertaking that it shall give in to the Bhutan Government a part of territory in the Assam State. The territory shall consist of 32.81 square miles which is known as Dowager situated at the border of district of Kamrup in the Assam State. The said territory had not been analyzed or the boundary was not fixed and hence was not transferred to the Government of Bhutan directly. Moreover, when the Constitution of India was enforced, Article 3 specifically provided that the undertaking given by the Indian Government required to be legally enforced by legislation passed by Parliament.

As the ceding of territory include the decrease of the part of the Indian Territory and making changes to the borders of Assam State, the decision of the concerned State legislature with regard to the suggestion to initiate a bill connected with the requirement and the terms that are determined as per the condition under the Article 3 of the Indian Constitution was essential. On March 27, 1951, the Assam legislative assembly implemented a resolution related with the cession. The assembly proposed to the Indian President to cede the territory to the Government of Bhutan. This was done as per the provisions of the Darjeeling Treaty concluded on August 8, 1949. The House advocated to convey 32 square miles of the area located under Dowager Hill block in the Assam State to the Bhutan Government. The bill was formulated to implement the transfer as per the provisions of the Constitution. Accordingly, the Act was framed to change the border of the Assam State resultant to the transfer of a part of the Assam State to the Bhutan Government.

The Act provides for the adjustment of existing boundaries of the State of Assam. From the initiation of the enactment, the area under the Assam State shall form part of the territory described under the Schedule as per Section 2 of the Act. Such territory shall thereafter form part of the Bhutan Government by cession. In accordance with this transfer, the borders of the Assam State shall be modified. The Act further provides for the amendment of the Schedule I under the Indian Constitution. Accordingly, under the Schedule I Part A Paragraph I of the Constitution, the Act excluded the area which are described under the Schedule provided under Assam (Alteration of Boundaries) Act, 1951 within the meaning of Tribal areas in the State of Assam coming under the title ‘Territories of the State’.

Moreover under Schedule I of the Act, the Act specifically describes the area to be transferred to the Government of Bhutan. In view of that, the area shall consists of narrow piece of the region that evaluates 32.81 square miles which is located at the southern part of State of Bhutan coming within the angles specified in the Schedule which is marked at the east, west and north directions and at the southern part with the use of pillars marked with numbers.

Therefore, boundaries of the Assam State were demarcated by a bilateral agreement concluded between the Bhutan Government and the Government of India. After the commencement of the Constitution, the alteration was effected after complying with the provisions of the Constitution.