Question: Since when has China been involved in negotiations to resolve its disputed land borders?
About the article "China", section "Territorial disputes".

Candidate passages:
In addition to claiming all of Taiwan, China has been involved in a number of other international territorial disputes.
Since the 1990s, China has been involved in negotiations to resolve its disputed land borders, including a disputed border with India and an undefined border with Bhutan.
China is additionally involved in multilateral disputes over the ownership of several small islands in the East and South China Seas, such as the Senkaku Islands and the Scarborough Shoal.
Malaysia is divided into thirteen states and three Federal Territories.
Eleven states and two Federal Territories are found in Peninsular Malaysia.
While two states and one Federal Territory are found in East Malaysia.
The states are further divided into administrative districts.
In Sabah and Sarawak, they are first divided into divisions, then further divided into districts.
There are separate subdivisions for electoral districts for polling purposes.
International borders between Malaysia and Indonesia, Thailand, Singapore and Brunei are defined mostly by geological features such as the Perlis River and Golok River between Malaysia and Thailand; Straits of Johor between Malaysia and Singapore; and Pagalayan Canal between Malaysia and Brunei.
However, borders that extends to the seas are defined by agreements such as Straits Settlement and Johore Territorial Waters Agreement of 1927 which defines Malaysia and Singapore water borders.
Malaysia's land borders are well established.
The border with Thailand was established in 1909 when Siam ceded Kedah, Kelantan, Perlis and Terengganu to the British.
Maritime border disputes between Brunei and Malaysia and a Bruneian claim on Limbang, Sarawak were resolved in an exchange of letters between the two countries on 16 March 2009 after 20 years of negotiations.
Malaysia and Indonesia have some overlapping maritime claims, notably in the area around Sabah.
An ongoing series of meetings to resolve these claims has produced 16 border agreements (to September 2010).
Malaysia and Singapore also have disputes concerning some maritime borders.
The Philippines has a dormant claim to the Malaysian state of Sabah.
Malaysia is also involved in a complex dispute, involving Vietnam, Brunei, the People's Republic of China, the Philippines, and the Republic of China (Taiwan), concerning the Spratly Islands in the South China Sea. 
Several countries have made competing territorial claims over the South China Sea.
Such disputes have been regarded as Asia's most potentially dangerous point of conflict.
Both People's Republic of China (PRC) and the Republic of China (ROC) claim almost the entire body as their own, demarcating their claims within what is known as the nine-dotted line, which claims overlap with virtually every other country in the region.
Competing claims include:  Indonesia, China, and Taiwan over waters NE of the Natuna Islands  The Philippines, China, and Taiwan over Scarborough Shoal.
Vietnam, China, and Taiwan over waters west of the Spratly Islands.
Some or all of the islands themselves are also disputed between Vietnam, China, Taiwan, Brunei, Malaysia, and the Philippines.
The Paracel Islands are disputed between the PRC/ROC and Vietnam.
Malaysia, Cambodia, Thailand and Vietnam over areas in the Gulf of Thailand.
Singapore and Malaysia along the Strait of Johore and the Strait of Singapore.
China and Vietnam have both been vigorous in prosecuting their claims.
The People's Republic of China and South Vietnam each controlled part of the Paracel Islands before 1974.
A brief conflict in 1974 resulted in 18 soldiers being killed, and China has controlled the whole of Paracel since then.
The Spratly Islands have been the site of a naval clash, in which over seventy Vietnamese sailors were killed just south of Chigua Reef in March 1988.
Disputing claimants regularly report clashes between naval vessels.ASEAN in general, and Malaysia in particular, has been keen to ensure that the territorial disputes within the South China Sea do not escalate into armed conflict.
As such, Joint Development Authorities have been set up in areas of overlapping claims to jointly develop the area and dividing the profits equally without settling the issue of sovereignty over the area.
This is true, particularly in the Gulf of Thailand.
Generally, China has preferred to resolve competing claims bi-laterally, while some ASEAN countries prefer multi-lateral talks, believing that they are disadvantaged in bi-lateral negotiations with the much larger China and that because many countries claim the same territory only multilateral talks could effectively resolve the competing claims.
The overlapping claims over Pedra Branca or Pulau Batu Putih including neighboring Middle Rocks by both Singapore and Malaysia were settled in 2008 by the International Court of Justice, awarding Pedra Branca/Pulau Batu Puteh to Singapore and Middle Rocks to Malaysia.
In July 2010, US Secretary of State Hillary Clinton called for the Peoples Republic of China to resolve the territorial dispute.
China responded by demanding the US keep out of the issue.
This came at a time when both countries have been engaging in naval exercises in a show of force to the opposing side, which increased tensions in the region.
The US Department of Defense released a statement on August 18 where it opposed the use of force to resolve the dispute, and accused China of assertive behaviour.
In May 2011, Chinese naval ships attacked and cut the cable of Vietnamese oil exploration ship.
This incidence sparked several protests against China in Vietnam.
On July 22, 2011, one of India's amphibious assault vessels, the INS Airavat which was on a friendly visit to Vietnam, was reportedly contacted at a distance of 45 nautical miles from the Vietnamese coast in the disputed South China Sea on an open radio channel by a vessel identifying itself as the Chinese Navy and stating that the ship was entering Chinese waters.
The spokesperson for the Indian Navy clarified that as no ship or aircraft was visible from INS Airavat it proceeded on her onward journey as scheduled.
The Indian Navy further clarified that "here was no confrontation involving the INS Airavat.
India supports freedom of navigation in international waters, including in the South China Sea, and the right of passage in accordance with accepted principles of international law.
These principles should be respected by all."
In September 2011, shortly after China and Vietnam had signed an agreement seeking to contain a dispute over the South China Sea, India's state-run explorer, Oil and Natural Gas Corporation (ONGC) said that its overseas investment arm ONGC Videsh Limited had signed a three-year deal with PetroVietnam for developing long-term cooperation in the oil sector and that it had accepted Vietnam's offer of exploration in certain specified blocks in the South China Sea.
In response, Chinese Foreign Ministry spokesperson Jiang Yu issued a protest.
The spokesman of the Ministry of External Affairs of the Government of India responded by saying that “The Chinese had concerns but we are going by what the Vietnamese authorities have told us and have conveyed this to the Chinese.” The Indo-Vietnamese deal was also denounced by the Chinese state-run newspaper Global Times. 
The South China Sea Islands consist of over 250 islands, atolls, cays, shoals, reefs, and sandbars in the South China Sea, most of which have no indigenous people, many of which are naturally under water at high tide, some of which are permanently submerged.
The features are grouped into three archipelagos (listed by area size), Macclesfield Bank and Scarborough Shoal, which collectively comprise a land surface area of about 15 km2 at low tide:   The Spratly Islands, disputed between the People's Republic of China, the Republic of China, and Vietnam, with Malaysia, Brunei, and the Philippines claiming part of the archipelago  The Paracel Islands, disputed between the People's Republic of China, the Republic of China, and Vietnam  The Pratas Islands, disputed between the People's Republic of China and the Republic of China  The Macclesfield Bank, disputed between the People's Republic of China, the Republic of China, the Philippines, and Vietnam.
The Scarborough Shoal, disputed between the People's Republic of China, the Philippines, and the Republic of China There are minerals, natural gas, and oil deposits on the islands and under their nearby seafloor, also an abundance of sealife, such as fish, animals and vegetation traditionally exploited as food by all the claimant nations for thousands of years - mostly without disputes that could risk war.
in the 20th Century, since the WW2 settlements failed to resolve ownership of such lesser areas of land, seas and islands, - and because of the economic, military, and transportational importance - their control, especially that of the Spratlys, has been in dispute between China and several Southeast Asian countries such as Vietnam from the mid-20th century onwards.
True occupation and control are shared between the claimants.
(See Claims and control below) 
During USSR's last years and after it dissolved it was highly important on the Russian agenda to settle the Russian-Sino border.
Gorbachev needed to substantially reduce Soviet troops on the border with China so that he could allocate national resources to a more urgent priority of the Soviet Union, its economy.
Against this background, In 1991, the Sino-Russian Border Agreement was signed apportioning territory that became contested during the Sino-Soviet border conflict.
The initial 1991 agreement left the most sensitive parts for a later stage.
The joint demarcation commission proceeded based on the terms stipulated in the 1991 agreement, and moved forward with a special emphasis on the technical aspects of hydrographic measurement and topography.
They also created practical solutions to address cross-border problems, such as several agreements onvisiting schemes for the two countries’ nationals to border areas, and joint economic use of parts of territories in Zabaykalsky Krai’.
On China’s side, the negotiations were affected by the Tiananmen incident in 1989 and Deng Xiaoping’s reform policy: the high priority placed on these internal tasks enhanced Chinese willingness to settle territorial disputes with Russia.
Uprisings in Xinjiang in the 1990s also pushed China to settlement with Kazakhstan, Kyrgyzstan, and Tajikistan on borders facing that province.
Chinese leaders were eager to gain support from the Kazakh, Kyrgyz, and Tajik governments to prevent separatism and the spread strengthening of pan-Islamic and pan-Turkic groups in Xinjiang.
In 1990–91, Russia and China agreed to withdraw their military from their heavily fortified positions along their extensive border, including in the sensitive Tumen River area.
Major navy and army facilities in Khasan District, Russia, were dismantled.
Sino-Russian border trade resumed as early as 1983–85, but accelerated in 1990–91, when border crossings were re-opened to private traders and travellers, Vladivostok was declared an open city, and foreigners were able to travel freely to the border regions of both countries.
In 1991, China also began a new round of economic reforms, and introduced new measures to accelerate foreign investment, which began to have a favourable impact in the Tumen River area.
Similarly, in early 1992, China announced border trade incentives and the introduction of special border economic zones along the Sino-Russian border, including its largest, in Hunchun.
On May 29, 1994 During the visit of Russian Prime Minister Viktor Chernomyrdin to Beijing, Russian and Chinese officials sign an Agreement on the Sino-Russian Border Management System intended to facilitate border trade and hinder criminal activity.
On September 3 that year, a demarcation agreement was signed fixing the boundary along a disputed 55-km stretch of the western Sino-Russian border.
In November 1997 at a summit meeting in Beijing, Yeltsin and Jiang Zemin signed an agreement settling the demarcation of the disputed 4300-km eastern sector of the Russian–Chinese border in accordance with the provisions of a May 1991 demarcation agreement between China and the Soviet Union.
The 2004 Complementary Agreement between the People's Republic of China and the Russian Federation on the Eastern Section of the China–Russia Boundary stated that Russia agrees to transfer a part of Abagaitu Islet, whole Yinlong (Tarabarov) Island, about a half of Bolshoy Ussuriysky Island and some adjacent islets to China.
A border dispute between Russia and China, standing since Japanese invasion of Manchuria of 1931, was resolved.
These Amur River islands were until then administered by Russia and claimed by China.
The event was meant to foster feelings of reconciliation and cooperation between the two countries by their leaders.
The transfer has been ratified by both the Chinese National People's Congress and the Russian State Duma.
The official transfer ceremony was held on-site October 14, 2008.
The Republic of China, based on Taiwan, refused to relinquish its claims to parts of disputed islands remained in Russian possession.