China and India have a complicated relationship. Both countries share a border longer that 2000 miles. In 1962 China and India fought the Sino-Indian War. China was able to control the territory of Aksai Chin. China lost 800 soldiers and India close to 1300.
In June 2020, in eastern Ladakh 20 Indian soldiers after a skirmish with Chinese Peoples's Liberation Army (PLA). In spite of these skirmishes, China and India are trying to have a cooperative relationship. Both countries are nuclear powers and cannot afford dangerous escalations.
Map of India and China obtained from Apple Maps. Note the poorly defined border
For further information, please read this article