Bindu Sampath listens over and over to a voicemail of the giggling granddaughter she's never met. She wonders if she ever will.

Sampath's daughter Nimisha, the child's mother, abruptly left their native India three years ago. She'd gone to dental school a few hundred miles north of their hometown in the southwestern state of Kerala. It was there that she met her future husband. She converted to Islam from Hinduism, and he from Christianity. Authorities say they both joined ISIS.

The 29-year-old dentist is believed to be in Afghanistan now. She and her husband are wanted by Indian authorities, who have charged them with conspiracy and ISIS membership. They're among dozens of people who've joined ISIS from northern Kerala in the past five years — more than anywhere else in India, according to a database of ISIS recruitment numbers in Indiacompiled by the Observer Research Foundation, an Indian think tank. Its tally is based on data from India's National Investigation Agency, the country's main counter-terrorism agency.

Most terrorism in India — the 2008 Mumbai attacks, for example — has been related to the India-Pakistan or Kashmir conflicts, or to a longtime territorial struggle by domestic Marxist guerrillas. India hasn't been a target for global jihad in the way Europe or the United States have. But neither had Sri Lanka, until this year's Easter bombings killed more than 250 people there, and ISIS claimed responsibility.

Sri Lankan authorities probing those Easter attacks have expanded their investigation to southern India, where officials say the alleged mastermind of the bombings had traveled. It's also where one of his followers was arrested in late April, accused of planning another suicide attack. Experts believe Sri Lanka, south India and the Indian Ocean region may be a new front for global jihad.

"This may be a message by the Islamic State, saying, 'Look, we are still alive and kicking. If you are pushing us out from Syria, we are very much alive in Sri Lanka. We are very much alive in South Asia,'" says S.D. Muni, a distinguished fellow at the Institute for Defence Studies and Analyses, a think tank in New Delhi.

For a while after she left India, Nimisha Sampath — who changed her name to Fatima Isa when she converted to Islam and got married — sent her mother text and voice messages from Afghanistan. They avoided discussing serious stuff. Bindu Sampath says she didn't want to ask too many questions. She just wanted to hear her daughter's voice.

In Afghanistan, Isa had given birth to a daughter. She sent photos of the little girl, whose third birthday is coming up this summer, and audio messages of her giggling.

Sampath says Indian authorities have informed her that her daughter and her family are involved with ISIS, though their exact role is unclear.

"I don't want to hear about the possibilities. I will be depressed — or commit suicide," says Sampath, 52, in a tearful interview at her southern Kerala home, where she also runs a makeup studio. "Only a mother can know how I am sacrificing. I say, 'God, please help her, please hold her.' "

Sampath keeps a framed photo of her granddaughter by her bed.

ISIS has radicalized people all over the world. But in India, stories from parents like Bindu Sampath have been very rare. Even with more than 180 million Muslims — one of the world's largest Muslim populations — India has had very few cases of radicalization.

"When Mahatma Gandhi launched his independence movement [in the early 20th century,] Indian Muslims were part and parcel of that movement, and from that time, politically and culturally, Indian Muslims have been well-integrated into the Indian mainstream," says Ashraf Kadakkal, a professor of Islamic and West Asian Studies at the University of Kerala.

But Kadakkal says that's changing now.

One possible contributing factor: Prime Minster Narendra Modi's Hindu nationalist Bharatiya Janata Party, which won power five years ago, has sought a bigger role for India's majority-Hindu faith in politics and public life. Many Indian Muslims and other minorities feel disenfranchised. In trying to make Hinduism more central to Indian identity,Kadakkal says the BJP has labeled Muslims as the "other."

"So this 'otherization' process has actually widened the division between the Muslims and Hindus, which may create an atmosphere in favor of fringe groups or radical groups," Kadakkal says.

ISIS recruitment has not been concentrated in northern India, though, where most of the country's Muslims live. It's happening in the south, which has stronger labor ties with the Persian Gulf. Millions of southern Indians work in the Middle East and send money home.

Kasaragod, the area of northern Kerala where Sampath's daughter is believed to have been radicalized, is prosperous, flush with remittances from the Gulf. From centuries-old spice routes to modern-day migrant workers, Kerala has historic and continuous ties to Gulf countries. Remittances, mostly from the Gulf, make up more than a third of the state's economy.

With Gulf money often comes Gulf values — especially for area Muslims, Kadakkal notes.

"They work in the Middle Eastern region and they come back with a new perspective," he says. "They consider the environment [in India] not to be Islamic. Here, you see the faces of women. You've got cinema, dance, drama — everything!"

That environment may be gradually changing in parts of Kerala. It's been a full generation since migrant workers began leaving to work in the Gulf and have since returned home with more conservative values. In Kasaragod, a district which 15 residents left three years ago to join ISIS in a single group, many women now wear full Muslim face veils, something that wasn't common previously. Over the decades, more mosques and Islamic schools have been built.

Experts say Gulf influence alone hasn't been enough to radicalize Indian Muslims, because they have been so well-integrated into Indian society. But with the recent rise of Hindu nationalism, Kadakkal says, radicalization is increasingly a fear.

Wealth earned in the Gulf is especially apparent in Kasaragod's huge marble villas, surrounded by swaying palm trees, next to white sand beaches.

On the porch of one such villa, a haggard-looking father in a white undershirt slumps in a plastic chair. He looks broken, describing how his two sons and a nephew were radicalized by a man who'd spent time in the Gulf and Sri Lanka. The man took them to Afghanistan, he says.

The young men were radicalized "through the Internet and also through their friends," says Abdul Rahman Paramban, a Kerala businessman who worked in the Gulf earlier in this own career. "Especially this one guy, Rashid. He left high-paying jobs in Dubai and Oman to accept a teaching job in our community. He's the one who brainwashed my boys."

That man he's referring to, Abdul Rashid, has since been charged with terrorism offenses. The record of charges against himsays he was previously kicked out of an "Arabic college" in Sri Lanka "for advocating violent jihad."

Paramban and local officials say that while working at a branch of the International Peace School in Kasaragod, Rashid befriended several local men in their 20s — including Paramban's sons and nephew — and helped radicalize them. Together they're believed to have traveled to Afghanistan in the summer of 2016.

At 68, Paramban wants to retire, but he has no other sons to take over the family hotel business. He's angry. His sons' first responsibility was to their family, he says.

These days, during the Muslim holy month of Ramadan, Paramban prays daily at his local mosque. It's a Salafi one, preaching a strict Saudi strain of Islam. That's one thing that's changed, he says, since he was born here in Kasaragod district.

His village of Padanna used to have only a few mosques, he says, and it's home to a 400-year-old shrine where a Sufi saint from Afghanistan is interred. Now there are more than two dozen mosques for a village of about 3,700 families.

The conservative Islamic atmosphere of Paramban's village is similar to that of the Sri Lankan town, Kattankudy, where the Easter bombings' mastermind grew up. Both areas are flush with Gulf money, and Gulf ideas. That, experts say, may make them fertile ground for the Islamic State's new recruitment drive.

Paramban has refused to exchange messages with his sons since they left India, but sad news reached him last year. His eldest son still exchanges text messages with some neighbors back home. Through those neighbors, the son sent word that his brother, Paramban's younger son, along with the man's wife and child, had all been killed in a U.S. drone strike.

As for Bindu Sampath — the Kerala grandmother who loves to hear the giggling voice of the granddaughter she's never met — she worries about a similar fate for her loved ones in Afghanistan. Six months ago, her daughter's phone went silent. Her last message came in November. There's been no contact since.

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