The police forces of two northeastern Indian states clashed at a contentious border area on July 26. The clashes between Assam and Mizoram police left six Assamese policemen dead and more than 70 people injured, prompting widespread anger among the Assamese people.  

In response, some Assamese residents blocked trucks transporting essential supplies, including medicines to treat COVID-19 patients, from entering Mizoram.

The incidents caused a major embarrassment to the federal government of Prime Minister Narendra Modi, which has deployed a "neutral force" at the frontier of the two states to prevent tensions from escalating.

Officials claim that the deadly incident was "in the past" and that tensions have died down, but, when visiting the border area, DW crew members noticed that tensions remain palpable.

A bus full of bullet marks

A bus used by Assamese police personnel on July 26 to go to the border to defuse escalating tensions remains parked on the highway.

The bus is full of bullet marks. It has "Mizoram" written over it to signify Mizoram's claims that Assamese police personnel had entered Mizoram's territory.

We were turned away from filming the border security checkpoints, which are guarded by central armed forces, but managed to take a picture of one of the border post structures that came under fire on July 26.

Central forces on both sides now act as a buffer between the police forces of the states.

How clashes turned deadly

Mizoram, a landlocked mountainous state of 1.1 million people, was part of Assam until 1972 and became a state in its own right in 1987. Assam is the region's largest state with over 30 million people.

Mizoram and Assam have been wrangling over their border for decades, but deadly escalations are rare.

The clashes turned deadly this time round because tensions had been simmering for a long time.

Though officials from Mizoram say Assam has encroached on the state's territory, their counterparts in Assam accuse Mizoram villagers of encroaching instead on reserve forest land.

At the time of the clashes, ministers from both states staged rival social media campaigns, sharing videos showing civilians armed with batons clashing with police and other violent scenes.

Vanlalfaka Ralte, a Mizo police officer in the district where the fighting took place, told DW that about 200 Assamese police personnel had come up "all of a sudden" on July 26 and pushed their way past security checkpoints.

Word spread and Mizo residents went to that checkpoint. They were met with violence there, according to Ralte.

British demarcation source of disagreements

The boundary dispute between Assam and Mizoram dates back decades.

Mizo officials argue that their state's boundary dates back to an 1875 notification that clearly demarcated Cachar plains in present-day Assam and Mizoram, which was then known as Lushai Hills.

But, according to the Assam government, the boundary between the states was established by a map drawn later by a British survey of India.

In 1933, the British demarcated the region into separate districts based on cultural, linguistic and tribal lines, leading to a new boundary separating Lushai Hills (present-day Mizoram), Cachar (Assam) and present-day Manipur.  

The Mizoram government rejects the 1933 demarcation, saying it was not done in proper consultation with Mizo leaders and that many of the Mizo-speaking districts went to Assam.

Dr. Charvak, a professor at the Assam University, said the "difference in perspective" between the sides "is the first root cause of the conflict." 

Region a hotbed of ethnic tensions

Following the deadly confrontations, the chief ministers of both states tweeted that they would seek an amicable approach to the dispute.

Assam Chief Minister Himanta Biswa Sarma belongs to Modi's ruling Bharatiya Janata Party (BJP) while Mizoram Chief Minister Zoramthanga heads the Mizo National Front — an ally of the ruling BJP alliance.

The border disputes in northeastern India, however, are not limited to Assam and Mizoram. Borders between the region's seven states are not clearly demarcated, and there are regular disputes over land and assets.

The resource-rich region has been a hotbed of ethnic tensions over the past few decades.