That border could get even more tense, with news like Google showing Arunachal as disputed territory. Now, a threatening email in Chinese is being circulated in India's north-eastern state
"All the tour operators in Arunachal Pradesh have received the threatening email. It shows all of Arunachal Pradesh as part of China; we are concerned," says Tsering Wange, Managing Director of Himalayan Holidays.
Three Maps are attached to the mail. One shows all of Arunachal within China, another marks Indian territory and the third marks New Delhi with a message in Chinese - that the People's Liberation Army needs just 2 days to occupy this place.
Wange has shown this email to authorities in Arunachal, but it is not known whether the state government has acted on it yet or shared it with the Centre.
"The Central government should act more seriously on this issue and should make this area more accessible to everybody. That way we can show to the world that this is very much part of India or else as now with the Restricted Area Permit (RAP) not many people can come," he says.
China also doesn't grant visas to the residents of Arunachal Pradesh, generally, and has allegedly scuttled development funding by international agencies like Asian Development Bank (ADB) and the World Bank in that state.
And with the Dalai Lama scheduled to visit Tawang in November, the MacMohan line continues to be the most precipitous fault line in India's defence and foreign policy.