evidence: Both countries’ troops have patrolled this region for decades, as the contested 2,200-mile border [PDF] is a long-standing subject of competing claims and tensions, including a brief war in 1962. The border, or Line of Actual Control, is not demarcated, and China and India have differing ideas of where it should be located, leading to regular border "transgressions." Often these don’t escalate tensions; a serious border standoff like the current one is less frequent, though this is the fourth since 2013. The Ladakh region is especially complex, with particularly unusual features. First, there is Aksai Chin, a territory that India has long claimed but China occupies. China began building a road through the area in 1956—linking Tibet to Xinjiang—and has occupied it since 1962. There is also territory that Pakistan ceded to China in 1963. Surveying and mapping the region’s terrain historically proved immensely challenging. A forthcoming history of the Ladakh region points out how colonial-era efforts to survey this area using natural features such as watersheds as focal points did not always align with cartographic needs for precision, and, importantly, ideas of where a country’s territory begins and ends.