The last time that I visited Flash and Knuckles in Cambridge, back in 2011, they had recently decided to join the international underground rap railroad.

“Before that we weren’t thinking about a wider spectrum,” says Flash, one half of the Cambridge duo Natural Born Spitters, better known as N.B.S. “It sort of isolated us from being world renowned when you had brothers like Termanology, and Reks, and Slaine, and Virtuoso, who were doing a lot of international stuff when we were doing local stuff.”

NBS is a tower of Hub rap ingenuity, an explosive mix of M.O.P. dramatics with the sociopolitical panache of Guru and Black Thought. Equally important is the hustle they endured to still be serving 15 years after their first release and to be dropping one of indie hip-hop’s toughest full-lengths this year—the long-awaited Trapped In America, on which they collaborated in full with European rap production powerhouse Snowgoons. Take it from Knuckles: “It took years to make something like this.”

Flash and Knuckles met Sicknature, now one quarter of Snowgoons, back in boom bap’s digital halcyon days on MySpace. It was before the Copenhagen-based MC/producer joined the Goonies, a primarily German outfit that’s adored by fans of Jedi Mind Tricks and other hardcore rhyme ambassadors, and his rise helped their plight as well. As recently as seven years ago, Flash and Knuckles nearly wound up getting left behind. In the time since, Snowgoons has built dozens of titanic beats for N.B.S., and helped the group become established overseas.

“When we first said that we were trapped in America, our goal was to be on tour,” says Flash. Their chance to flee came in 2012, when Snowgoons asked Virtuoso, a labelmate of N.B.S. on Big Bang Records, to rock at the annual Hip Hop Kemp blowout in the Czech Republic. But after being promised two guest spots to perform at the festival, they almost watched hope slip away when Knuckles got completely smashed and disappeared for an entire day. In something of a cross between Sex Pistols American tour lore and the Denzel Washington film Flight, N.B.S. miraculously managed to rally and knock out two sets plus an after-party.

On the strength of contacts made at Hip Hop Kemp, Flash and Knuckles took off on their debut European club tour less than six weeks later, and the following year flew to Japan for a month, then China, and have since made globetrotting a routine. “The crowds are live,” Knuckles says. “They interact. They might not understand what you’re saying, but they know your shit is jumpin’. This is our motivation now—to get other people to travel.”

“There’s a lot of people who don’t even have passports,” Flash adds. “When we’re traveling, people are always calling us and telling us to look out for ISIS and shit. When you’re there, though, it’s a lot of love.”

N.B.S. + SNOWGOONS. THUR 7.2. MIDDLE EAST UPSTAIRS, 472 MASS AVE., CAMBRIDGE. 617-864-EAST. 8PM/18+/$13. MIDEASTCLUB.COM.