Five centimetres tall, the golden "Aphrodite of Bactria" rests a bangled hand on an ultra-curvy hip, Bollywood style. Below, her Greek gown swirls, and wings sprout from Olympian shoulders.
It's Classical civilisation, but not quite as we know it: on her forehead is a prominent Indian bindi mark. Near her, on glass goblets painted in riotous blues and yellows, nymphs and swains gather in the vintage, but with palm fronds in the background of their idyll: grapes or dates?
A plaster-cast medallion, a smug pretty-boy ties his long hair back in a band with a show-off seductiveness that might have shocked Mediterranean fans of cropped warrior youths. An Indian ivory nymph boasts a beyond-hourglass figure and fails to hide it, not with a dhoti but diaphanous Greek drapery. And the shimmering gold crown of a nomad princess turns out to be a fold-away marvel made of five detachable sections: portable bling by an antique Ikea. On her chest, for the journey to the otherworld, this wandering diva bore a Chinese mirror. Where are we, as so many strands of East and West entwine? In Afghanistan, two millennia ago.
Afghanistan: Crossroads of the Ancient World has rightly caused a stir for its humbling backstory. Between the Soviet invasion of 1979 and the fall of the Taliban regime, the National Museum in Kabul – home of these 230 or so treasures – suffered every hardship and indignity a storehouse of culture can endure, including near-total devastation. Much was lost but, from the director down, the staff secreted away in underground vaults, hotel cellars and even their own homes thousands of objects that made up the precious evidence of Afghanistan as a nursery of culture, not a killing-ground.
It took until 2004 to complete the long haul of recovery. Then, in 2006, the show that celebrates this miracle of survival began its tour in Paris. The people who bring it to you now are heroes of archaeology in ways that dwarf even Indiana Jones.
The British Museum exhibition, of a manageable size, highlights finds from four sites in northern Afghan-istan excavated between the 1930s and 1970s. In this region, the multiple paths of the Silk Road criss-crossed as they snaked between China and the Med. Forlorn, barren, windswept wilderness? Forget it. Two thousand years ago, this patch was a multicultural hub. In the first century AD, you might serve meals from the same ribbed-glass bowl in Bath as in Begram, north of Kabul.
The outlier cache here originates in Tepe Fullol, a Bronze Age burial hoard of golden goods dated to 2000BC. These sumptuous fragments tell not of desert isolation but a network of trade from Mesopotamia to India. The other three movements of this cosmopolitan quartet range in time from the third century BC to the first AD. At Aï Khanum a Hellenistic city flourished, one of many founded in Bactria by Alexander the Great's troops. Here, a year's march from the heartland, bearded stone sages preside over the mind-and-body "gymnasium" and bronze Heracles swings his club. Yet a gilded plate fuses Greek and Asian motifs: hey, we're not in Macedonia any more.
Aï Khanum fell in 145BC to nomad tribes. If you had the scary horsemen marked down as barbarians, think again. Two treasure-packed storerooms found intact at Begram prove that, 2,000 years ago, the Kushan dynasty had not only settled down and grown rich, but forged trade links with every chic supplier of luxury items from China to Rome. Was this a palace or – as now seems more likely – a high-value bonded warehouse? Whatever: enjoy the Roman-Egyptian glass, the sturdy Greek bronze figures, and the frisky Indian maidens semi-nude on ivory plaques. In a medallion of Eros and Psyche, the infant love-god seems to struggle free of his setting.
We end in a fabulous shower of gold. But the six nomad tombs of Tillya Tepe (around AD50) astonish most not by weight of carats but their workmanship. Others will swoon over that five-part turquoise-inlaid crown. I left haunted by the transfixing gaze of a little horned ram, a headdress ornament, every detail of his wool, muzzle and muscles picked out. Our hyper-alert ram matches no known imported style. He belongs to Afghanistan.
Until 3 July (020-7323 8181)
Charles Darwent dips into the Ashcan Painters, at the National Gallery
EO Hoppe's photographs capture between-the-wars Britain, and a raft of famous faces from George VI to George Bernard Shaw (at the National Portrait Gallery, London, to 29 May). And prepare to be bowled over by Cory Arcangel at the Barbican's Curve gallery: he's projected 14 giant bowling video games, all impossible to win (to 22 May).