In case you are wondering about the third line, that is never shown anywhere, it is the only one that is the subject of a settlement of the borders between Tibet and Ladakh.
In 1842, a brilliant Dogra General, Zorawar Singh, mounted his last campaign for his master, the Dogra chief of Jammu, the Raja of Jammu, a vassal of Ranjit Singh, the great Sikh ruler who ruled from Lahore. He had earlier fought and won Baltistan and Ladakh for Gulab Singh, the Raja of Jammu. This, added to earlier conquests, formed a hollow ring around the Vale of Kashmir, that was ruled by a separate governor for the great Sikh ruler.
So now Zorawar Singh set out to conquer Tibet.
He won some battles in western Tibet, but could not make much progress, as he was trapped by winter. His soldiers were soon burning their musket stocks to stay alive. A joint Sino-Tibetan team then fought and defeated the Dogra army. They killed Zorawar Singh; some stories say that they ate his heart to try and gain his courage for themselves! Some part of the Army fled down into the Himachal area, and circled around to march on Leh. The Sino-Tibetan army marched to Leh and attacked the Dogras there. The survivors of the earlier attack rejoined the main Dogra forces at Leh, and the combined forces beat the Sino-Tibetans, killing the Chinese Ambon, or delegate to Tibet.
Since both armies had fought themselves to a stand still, the Tibetans agreed to return, and they, and the Dogras+ Ladakhis, signed the Treaty of Chushul, agreeing by their gods never to violate the traditional boundaries. Sadly, they never described those boundaries; if they had, it would have saved a great deal of trouble.