China’s Arunachal Pradesh Claim and International Law: Sovereignty, History, and Boundaries

China’s assertion on Arunachal Pradesh, which it calls “Zangnan” (South Tibet), is based on historical ties to Tibet and a rejection of the 1914 Simla (Shimla) Convention. China repeatedly frames Arunachal as a legacy of past Tibetan administration; official commentary observes that historically the local Monpa population were “Tibetan subjects” paying tribute to Lhasa, and that Tawang region affairs were handled under Tibetan (and by extension Chinese) jurisdiction.

Illustration by The Geostrata

On the other hand, India administers Arunachal and rejects China’s claim. In international law, territorial claims require a clear legal title or effective sovereignty on the ground, not just historical assertions. Under established principles, China’s claim to Arunachal has weak legal standing.

Key principles such as uti possidetis juris, effectivités (actual control), and the rejection of purely historical claims strongly favour India’s title. In practice, no treaty cedes Arunachal to China; India maintains continuous administration there, and even China’s official stance (calling India’s control “illegal”) is at odds with international legal norms.

HISTORICAL BACKGROUND

The modern dispute traces to the 1913–1914 Simla Convention. British India and Tibet agreed on the McMahon Line as the India–Tibet frontier. China did not sign that treaty, insisting Tibet was part of China. As Britannica notes, “Although the British Empire and Tibet accepted the terms, China refused to sign… because it believed that Tibet was an integral part of China and had no power to enter into treaties”. 

After the People’s Republic of China (PRC) took control of Tibet in 1950–51, it continued to reject the McMahon Line. Chinese Premier Zhou Enlai later called it a product of “imperialist aggression” that was “decidedly illegal.

In 1962, China briefly occupied parts of Arunachal but ultimately withdrew, and India has since administered the region. China also points to earlier agreements: it highlights the 1890 Anglo-Chinese Convention on Tibet and Sikkim, which defined the Sikkim-Tibet boundary, and claims that India’s later inheritance of British lines ignored China’s historic frontiers.

China’s maps, however, continue to depict it as part of Tibet (and hence China). India has reiterated that Arunachal “has always been an integral and inalienable part of India”, while China accuses India of “illegal occupation” of Chinese territory. In diplomatic practice, most countries (e.g. the United States) treat Arunachal as Indian territory, and the dispute remains bilateral and unresolved by any international tribunal.

KEY LEGAL PRINCIPLES IN BOUNDARY DISPUTES

Territorial disputes are settled by reference to international law principles and evidence of sovereignty. Three key principles guide this analysis:

Uti Possidetis Juris: This decolonisation principle holds that newly independent states inherit the borders of their predecessor administrations. The ICJ has explained that uti possidetis “accords pre-eminence to legal title over effective possession” to secure respect for the boundaries existing at independence.

In Frontier Dispute (Burkina Faso v. Mali) (1986), the Court emphasised that colonial boundaries become international frontiers upon independence.

Applying this to India, the borders drawn by British India (including the McMahon Line with Tibet) would generally fix India’s frontier at independence. In other words, India extends to the boundary of British India in the northeast. While China never agreed to the McMahon Line treaty, it never provided an alternative recognised boundary either. In practice, then, the colonial-era demarcation (whatever its disputed legal status) has remained in force.

Effectivités (Effective Control): International law also looks at which state exercises authority over a territory. Courts have held that a state’s “continuous and peaceful display of territorial sovereignty” can create a stronger claim than mere historical title. By contrast, India has administered Arunachal Pradesh continuously since independence (or earlier under the British). Indian laws apply there, local elections are held, and India maintains infrastructure and security.

China has no parallel administration on the ground. This effectivités strongly favours India’s claim to sovereignty. India evidently meets this test in Arunachal. In short, the state that holds the territory and governs it uninterruptedly (India) has the stronger title under international law.

In this light, China emphasises that it exercised effective administration over Zangnan until Indian forces entered in 1962. Beijing states that the actions, such as patrolling and local governance, it used to perform before 1962, are proof of sovereignty.

Rejection of Purely “Historical” Claims: Claims based only on distant history are not sufficient to alter borders in modern law. In Arunachal’s case, China’s argument relies on a historical view that parts of Tibetan-administered territory once extended into what is now Arunachal. But international adjudicators require a clear legal title (e.g. by treaty) and/or continuous authority. Historical assertions without treaty support are generally dismissed.

China has never produced a valid treaty transfer of Arunachal to China; nor did its rule (through Tibet) ever match India’s long-standing control and administration. Thus, China’s historical claim, absent effective occupation or mutual agreement, carries little weight under international law.

If tested in court, concepts of effectivités (actual governance) would weigh heavily. Inter-temporal logic thus creates a dilemma that China’s historic links date from Qing times, but India’s uninterrupted rule for 70+ years is also a powerful legal fact.

CHINA'S POSITION

The PRC maintains that “Zangnan” (Arunachal Pradesh) has historically belonged to China. Official Chinese statements describe it as Chinese territory and part of Tibet. In 2024, a Chinese Foreign Ministry spokesperson reiterated that “Zangnan is part of China’s territory” and that China once “exercised effective administrative jurisdiction” there before India’s alleged “illegal occupation”. 

Chinese media and officials routinely refer to Arunachal as “South Tibet” and argue that India’s creation of the state of Arunachal Pradesh in 1987 was “illegal and null and void”.

Beijing often invokes maps and historical records to support this. One analysis points out that “China bases its claims on historical maps and treaties, asserting that ‘South Tibet’ was wrongfully incorporated into Indian territory” after 1947.

INDIA'S POSITION AND INTERNATIONAL SUPPORT

India firmly rejects China’s claims. The Indian government insists Arunachal is an integral part of India. In official statements, New Delhi has “categorically” rejected the Chinese renaming of places in Arunachal. India’s foreign ministry has called China’s assertions “absurd” and repeatedly emphasised that Arunachal “has always been part of India”. India relies on the fact that the entire area has been administered by India (and before 1947 by British India) for decades.

India also points to international practice: most governments and analysts treat Arunachal as Indian territory.

The United States, for example, publicly “recognises Arunachal Pradesh as Indian territory” and “strongly opposes any unilateral attempts” to change this. On legal grounds, India argues that the McMahon Line, the line drawn with Tibet, marks its northern border.

India views the 1914 Simla Convention (even unratified by China) as binding in effect because Tibet’s signatories recognised the line. From India’s perspective, the Treaty of 1914 and the continuity of administration since then confer title. Combined with India’s decades of effectivités in Arunachal, India holds that international law fully upholds its sovereignty there.

FUTURE OUTLOOK?

The border dispute over Arunachal Pradesh remains a sensitive bilateral issue. It has periodically flared into military standoffs, such as the 1962 war and more recent patrol clashes. Both governments publicly manage the tension; they hold periodic talks and have mechanisms (e.g. hotlines, flag meetings) to prevent incidents. Despite this, India and China continue dialogue on various fronts (economics, trade, multilateral forums…).

Internationally, the issue is usually treated as a matter of dispute over a bilateral border line, not a justified change of sovereignty. International law offers tools like treaty interpretation and the inter-temporal rule to analyse these arguments, but without a negotiated settlement or neutral adjudication, both narratives remain in conflict. 

The dispute thus endures as a live example of how colonial-era agreements, historic titles, and evolving rules of law intersect in modern boundary disputes. Any durable resolution will require China and India to negotiate a border settlement; until then, international law demands that neither side change the ground situation unilaterally.

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BY SANOOP SAJAN KOSHY

COVERING PEOPLE'S REPUBLIC OF CHINA

TEAM GEOSTRATA

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