Radio / Way out west: Robert Hanks on the disappearing Jews of Yemen and the Mormon cowboys of Utah

You wonder how Tudor Parfitt's advertisements would look: 'Lost tribes traced. Israelites a speciality.' A few months ago he recorded his search for the lost Jews of southern Africa, in King Solomon's Tribe. Last week, in The Longest Exile (Radio 4, Thursday), he went after the Jews of Yemen - not so much lost, to be sure, but quietly disappearing.

Yemen is a country with a strong tradition of exiling, taxing and generally making life insupportable for its Jewish population. An American living there told how an Arab showing him around had pointed out the coolest part of town - you always knew the cool places, the Arab said, because the Jews lived there. This sounded complimentary, but what he turned out to mean was that Jews always lived somewhere where they wouldn't get too sweaty, because otherwise they stank, even if they had baths. Not that that's relevant in Yemen, where Jews are banned from the communal bath-houses.

Most Jews left for Israel in 1948, in an airlift seductively codenamed Operation Magic Carpet. The few remaining are set to follow, which seemed like the most sensible move. But the Promised Land also has its threats, especially for the women. Unlike the men, they aren't allowed to learn Hebrew (or anything else, in fact), and polygamy puts them at a disadvantage: one woman who shared her husband with a younger, prettier wife was terrified of moving to Israel, where he might have to make a choice.

What seemed to begin as a programme about race turned into something subtler - a sketch of the way that the 20th century sometimes intrudes on earlier centuries; and nobody comes out of it terribly well. It wasn't an entirely satisfactory programme, meandering and unfocused; but it said a lot - perhaps more than it meant to - about the contrast between the developing world and the sophisticated West.

Meanwhile, the new Classic Serial, Riders of the Purple Sage (Radio 4, Sunday), travels to the completely unsophisticated West. There are faint echoes of The Longest Exile here. Zane Gray's classic western replaces the usual cowboys and indians combination with Mormons and Gentiles. The Mormons believe that the American Indians were a lost tribe of Israel; and in the Utah of 1871, according to Gray, they practised their own version of apartheid, barring non-Mormons from land and employment.

The treatment doesn't live up to the gravity of the themes, partly because it's always hard to take Mormonism entirely seriously. Granted, the mythology of angels and gold tablets and lost tribes isn't uniquely implausible - on strictly empirical grounds, most of the world's major religions look pretty unconvincing; but other world religions don't have to cope with the stigma of having produced the Osmonds.

Adrian Bean's production resists the air of the ridiculous manfully, though, and the story is a cracker: evil Mormons in conflict with enigmatic nemesis Lassiter and his menacing black guns. The natural home of the western is the cinema; but at the moment, the cinema has absorbed too much irony, and too much guilt, to be able to do an old-fashioned western properly. On radio, the Wild West is still virgin territory, where even the cliches sound fresh.