The Swing Thing (BBC4, 9.30pm); Unreported World (C4, 7.35pm)

IT was billed as “dangerous music that made you have sex with people”.

This was regarded as a bad thing, with one psychiatrist claiming, “It is like taking a drug”.

The “it” is swing, the blend of orchestrated big band sound and improvised jazz that flourished in the Prohibition speakeasys, was hampered by America’s racial issues and only became respectable when Benny Goodman played it in the pre-Second World War period.

The Swing Thing is one of those pleasant surprises, a documentary that informs and entertains in equal measure.

The story of swing is, we’re told, “about poverty, crime and sex, but chiefly sex”. No wonder it provoked the world’s first youth cultural revolution.

Through archive film and interviews, plus contributions from the likes of Johnny Dankworth and Jools Holland, this is a thorough exploration of swing from the jazz clubs of the 1920s to the modern day.

Some names – like Louis Armstrong, who provided the inspiration for swing at a time when music was segregated – you’ll recognise, while others, like Fletcher Henderson, won’t be so familiar.

Harlem in the 1920s was the one place black people could go and be free. Poets, singers and writers congregated there.

From this artistic melting pot emerged Duke Ellington, who took swing to a whole new level.

By the end of the decade, swing was the strongest form of jazz. People danced to this “music of black self-expression” or listened to it on the radio on a Saturday night. “You couldn’t listen to the music and not dance to it,” as one interviewee puts it.

Charleston, the most popular dance of the day, was adapted to swing and the lindy hop was born, an energetic mix of organised and improvised dance.

One of the most famous venues was the Cotton Club, owned by a British-born gangster. Musician Duke Ellington recalled during a TV interview with Michael Parkinson how no one was allowed to talk during the show. Waiters would tell talkers off, if they continued to talk they’d simply “disappear”.

Black performers found themselves in an odd position. They could work in the Cotton Club, but not go there as it was strictly white audiences, black performers.

It took Benny Goodman to get mainstream America to embrace swing. He employed black musicians in his band, although replaced them with white players on tour.

Swing has endured for nearly 100 years, with the likes of Robbie Williams and Michael Buble carrying on the tradition today.

Unreported World continues to go where the travel brochures don’t dare.

Culiacan, in the North-West state of Sinaloa, in Mexico, is the scene of a drug trafficking cartel war. So far this year, 560 people have been killed, including 90 police officers. Reporter Evan Williams spends seven days on the front line with a driver, Fidel, who has such good contacts that they often arrive at the crime scene before the police.

They are not pleasant places. Within five minutes of the start of the programme, we’ve seen the corpse of a young man, hands tied and shot in the head, and an 18-year-old man taken from his bed by eight armed men and executed at point-blank range.

The corpses mount up as the report progresses. On day five, Williams finds himself viewing five dead bodies in the middle of the countryside. The evidence shows they were lined up and executed one by one.

Two years ago the Mexican army was deployed to help police stamp out the drug trafficking war. They don’t seem to be doing very well.

Human rights campaigners and grieving relatives are among the few people who speak out against the violence. A member of the state parliament to whom Williams speaks won’t talk indoors because she doesn’t trust the people inside.

That may be because the money from the drugs trade is used to back politicians.

After seven bloody days, Williams knows more about the situation but a solution seems as far away as ever.