Where exactly is the border line between India and China

In various maps of the first half of the last century, including maps of India, the boundary between India and China roughly follows the line where the southern foothills of the Himalayas meet the plains on the north bank of the Brahmaputra River, and the area north of this traditional customary line has long been under the administrative jurisdiction of China. The drawing of the eastern section of the border in the "Administrative Map of India" published in 1905 corresponds to the Chinese map, and the eastern section of the Sino-Indian border in the Chinese map in the Encyclopaedia Britannica (14th ed.) of 1929 corresponds to the map published in China. The so-called "McMahon Line" pushed the "border" northward by about 100 kilometers, roughly along the Himalayan ridgeline, and assigned 90,000 square kilometers of land that had long belonged to China to British India. Historically, only customary boundaries have existed along the Sino-Indian border. Western Sector: the part of China's Xinjiang and Tibet bordering India's Ladakh region, mainly bounded by the Karakoram Mountains, with 33,000 square kilometers of disputed territory, mainly in China's Aksai Chin region. Of these, India occupies one site in the Parigas, the rest are controlled in the hands of China. The focus of the dispute is to the north of the Kungkha Pass, traditionally the lifeblood of transportation between Tibet's Ali and Xinjiang. 1959 saw the beginning of Indian incursions into this area. Central Sector: Tibet borders India's Punjab and other areas. 2100 square kilometers of disputed territory, divided into 4 places, all occupied by India. 1954 India began to invade this area. Eastern Sector: Tibet shares a border with the Indian state of Aslam, with 90,000 square kilometers of disputed territory, all of which is occupied by India. East of Bhutan and west of Burma is the most disputed section of the border; a Sino-British conference on Tibet was held in Silam in 1914, after which the British representative, Henry McMahon, secretly met with Tibetan representatives. McMahon and Tibetan representatives secretly drew an illegal line on the Sino-Indian border east of Bhutan. After World War II, India began to cross the traditional customary boundaries of China at the southern foot of the Himalayas to reach the northern part of the area, and in 1954, it completely occupied the Chinese territory south of the McMahon Line.