 Their first formal codification in treaty form was in an agreement between China and India in 1954 which recognized Chinese sovereignty over Tibet.They were enunciated in the preamble to the "Agreement (with exchange of notes) on trade and intercourse between Tibet Region of China and India", which was signed at Peking on 29 April 1954.Negotiations took place in Delhi from December 1953 to April 1954 between the Delegation of the PRC Government and the Delegation of the Indian Government on the relations between the two countries with respect to the disputed territories of Aksai Chin and South Tibet.