Pakistani demonstrators take part in a protest in Karachi against the Burmese government over the treatment of Rohingya Muslims on Sunday. (Rizwan Tabassum/AFP/Getty Images)

Until recently, most Pakistanis knew little to nothing about the problems of Rohingya Muslims in Burma. They could talk in great detail about the plight of Muslims in Indian Kashmir and were familiar with an array of international Muslim causes, such as Palestinian rights or the Arab Spring. But the Rohingya story was almost unknown here.

Except in one place: an impoverished pocket of Karachi, the huge port city on the Arabian Sea, where tens of thousands of Rohingya migrants have lived peacefully for half a century, working on fishing boats or docks. The older ones originally fled a repressive military regime, escaping on foot or by boat.

Two weeks ago, word began to reach the Rohingya community in Karachi that something terrible was happening in their homeland. On social media, relatives described military troops raiding and torching homes in Burma's Rakhine state. News videos showed thousands of people leaving. Soon almost 300,000 had fled to Bangladesh, a coastal neighbor on the Bay of Bengal that was once part of Pakistan.

In Karachi, a Rohingya fisherman named Noor Mohammed, 50, told a news agency that three members of his family were killed in Rakhine during the previous week. A woman said her sister had tried to reach Bangladesh by boat but was being held by boat owners demanding a large payment. 

The Rohingya Muslims are a stateless minority in Buddhist-majority Burma, also known as Myanmar, which has a powerful military. After political violence erupted in August, the military said its crackdown was in response to insurgent attacks on police posts. On Tuesday, the U.N. high commissioner for human rights called the repression "a textbook example of ethnic cleansing."

Demonstrators in Karachi protest violence against Rohingya Muslims on Sunday. (Shahzaib Akber/EPA-EFE)

By last week, the outrage had spread far beyond Karachi's fishing community. In cities and towns across Pakistan, people suddenly were organizing demonstrations to protest the Rohingyas' plight — lawyers, tradesmen, civic groups, clerics, journalists, tribal leaders and university communities all joined in. The phrase "Rohingya genocide" flashed across nightly newscasts. 

"This is a human crisis of grave proportions. It is hard for me to believe what I am reading, hearing and watching," said ­Sajid Ishaq, chairman of the Pakistan Interfaith League. "I urge the U.N. to stir from its slumber and react as it did in the case of East Timor," he said. The former Portuguese colony faced bloody suppression in a struggle for independence from Indonesia, which it won in 2002. 

On Friday, thousands of demonstrators converged on Islamabad, Pakistan's capital, after weekly prayer ceremonies, clashing with riot police near the high-security diplomatic zone. They attempted to reach Burma's embassy but were stopped by shipping containers placed across key streets. The march turned into a peaceful sit-in that lasted until late evening.

On Monday, leaders from religious and secular political parties joined rallies across Khyber Pakhtunkhwa province to urge the "civilized world to stop the mass execution of Burmese ­Muslims"; call on the government to cut ties with Burma; and condemn Aung San Suu Kyi, Burma's de facto leader and former democratic crusader, for her "criminal silence" on the repression. 

Pakistani officials, while trying to contain public demonstrations, lodged formal protests with Burmese diplomats. Prime Minister Shahid Khaqan Abbasi and his cabinet, after meeting over the weekend, said in a statement that the "brutal and barbaric acts" against the unarmed civilian population constituted "state terrorism." 

Demonstrations also erupted in numerous other Muslim communities, including in Ukraine and Indonesia. In Afghanistan, protesters rallied last weekend in the capital, Kabul, holding up posters that said "Stop Killing Muslims" and called Suu Kyi a "satanic" criminal. Suu Kyi's campaign for democracy won her the 1991 Nobel Peace Prize, which some critics said should now be revoked.

In an odd twist, an Islamist party in Afghanistan, Hezb-i-Islami, this month blamed the Taliban for spurring anti-Muslim violence in Burma when the group destroyed the famous Buddha statues of Bamian in 2001. Taliban officials in turn said they welcomed the show of international support for "the Muslims of Burma." 

In Pakistan, the most powerful criticism came from Malala Yousafzai, an activist for girls' education who won the Nobel Peace Prize in 2014 after she survived a Taliban attack. In a statement, she said she had "repeatedly condemned" the "tragic and shameful treatment" of the Rohingya in Burma. "I am still waiting for my fellow Nobel laureate Aung San Suu Kyi to do the same."