Factbox: India's remote, undefined Himalayan border with China

Scuffles broke out last week between Chinese and Indian frontier guards at the eastern end of the long Himalayan border between the nuclear-armed Asian nations, in the first such clash since 2020.

The Dec 9 scuffle occurred at the Tawang sector of India's northeastern state of Arunachal Pradesh, which China also claims. India says its soldiers prevented Chinese soldiers from entering Indian territory, while China says the Indian troops illegally crossed the border to stop a routine patrol of its soldiers.

India said soldiers from both sides suffered minor injuries. The incident was minor in comparison to the clash at the western end of the border in 2020, when 20 Indian soldiers and four Chinese troops were killed.

Here are some facts about the Indian-Chinese border area:

*China and India lay claim over vast swathes of territory along their 3,500km-long de facto border, called the Line of Actual Control. The Himalayan area is largely remote, rugged and snow capped, with soldiers from both sides facing off just a few metres away from each other in several areas.

*The border was never officially demarcated. India's former British colonial rulers saw little need to demarcate such a remote area and after India became independent, both nations could not agree on a common frontier.

* Years of border disputes escalated into a full-scale war in 1962 after India said China occupied 38,000 square km of territory in Aksai Chin, which New Delhi claimed as part of its Ladakh region. The war was primarily fought in Aksai Chin, at the western end of the Himalayas, and Arunchal Pradesh at the eastern end.

The frontier has remained largely peaceful since then and in 2000, after two decades of talks, India and China exchanged maps on the least controversial middle segment of the frontier. In 2003, special envoys were tasked with resolving the dispute but nearly a decade later, the border remains undefined.

*In 2020, Indian and Chinese troops were involved in hand-to-hand combat in the Galwan Valley of Ladakh, an area near the Chinese-held Tibetan plateau. Twenty Indian soldiers and four Chinese troops were killed in the fighting, the deadliest along the frontier for decades. The incident strained Sino-Indian relations.

*India's borders with neighbouring Pakistan, an ally of China, are also disputed. Both nuclear-armed nations lay claim over Kashmir, a region that has been a flashpoint since they gained independence from Britain, and they have fought two wars over it. Last year, top intelligence officials from Pakistan and India met to try and break the impasse over Kashmir.

- Reuters