evidence: Bhutan and China had long had differences with respect to the delineation of their common border, which follows natural featuresthe watershed of the Chumbi Valley in the northwest and the crest of the Great Himalayan Range of mountains in the north. China and Bhutan have two border disputes Kula Kangri Mountain and parts of Haa district of Bhutan, both controlled by China and claimed by Bhutan. Beijings policy in the Himalayan frontier region was to claim disputed areas on the basis of usage by Tibetans. The two countries share about 470 km long contiguous borders and have held several rounds of talks to resolve the dispute and signed for the first time an agreement promising to 'Maintain Peace and Tranquillity on the Bhutan-China Border Areas,' in 1998.