› Central Asia is a breeding ground for militancy,

KIEV, Ukraine — The terrorist attack in New York on Tuesday was carried out by a young man from Central Asia, a former backyard of the Soviet Union known for poverty, isolation and repressive governments — all elements in breeding some of the most militant Islamist activity in the world.

Since the fall of the Soviet Union, Islamist insurgencies have erupted throughout the region, most notably in the Caucasus and the suspect’s native Uzbekistan. While those insurgencies have been mostly suppressed, often with unflinching brutality, analysts have grown increasingly concerned about Islamist radicalism spreading out of the region as young men leave in search of work.

This is particularly true, analysts say, of Uzbekistan, where a blend of repressive politics and economic failure has generated a steady outflow of both migrants and militants. Many of the immigrants have come to the United States — nearly 60,000 as of 2013, the American Community Survey said, with about half of them going to New York City.

Under a new president, Shavkat Mirziyoyev, Uzbekistan has recently eased its iron grip over its citizens. Mirziyoyev has offered to help the U.S. authorities investigate the attack, and in a statement offered condolences. “This merciless and very cruel crime cannot have any justification,” he said.

Central Asians account for a significant portion of the foreign fighters who joined the Islamic State militant group in Syria, making their common language of Russian second only to Arabic in the group’s propaganda and communications. The International Crisis Group, a research organization, has estimated 2,000 to 4,000 Central Asians have joined the Islamic State and other Islamist groups.

While there is no saying, for now, what may have motivated Sayfullo Saipov, the suspect who is thought to have driven the truck that plowed through a bike lane in Manhattan on Tuesday, killing eight people, Central Asia’s troubled politics and economics form a part, at least, of the back story.

The expanse of desert and mountains north of Afghanistan has a total population of about 60 million. Uzbekistan, with around 32 million people, is by far the most populous, and has a long history with Islamist militancy.

A spiral of repression and radicalization that has spawned three major Islamist groups began soon after the Soviet breakup, as an Islamic revival filled the vacuum left by Communism.

Proselytizing by Saudi-financed groups advocated a particularly austere form of Islam, and a renewed interest in Islam in much of the former Soviet space sped things along.

“Of course, when one ideology falls, another one takes over,” Shahida Tulaganova, a former producer with BBC from Uzbekistan, and a close observer of Islamist movements in the region, said in a telephone interview.