A golden silk shirt woven more than 1,000 years ago, which was among the greatest treasures of the nomadic Sogdian people, is coming up for auction valued at up to £500,000.

The garment features a pattern of ducks wearing fluttering scarves – a sign, with the jewelled necklaces they carry in their beaks, that they belonged to the royal household.

“There are hardly any of these garments outside museums, and the condition of this one is extraordinary – they were known and coveted as cloth of gold and although it is entirely woven of silk, after 1,000 years it still really does look as if it was made of real gold,” said Alexandra Roy, the deputy director of the Middle East department at Sotheby’s.

The shirt, which could have been traded or a gift of the highest status, was clearly once worn by somebody, since despite the condition of the silk there is some wear at the armpits and belt level.

The Sogdians, centred on modern Uzbekistan and Tajikistan, were known for their magnificent textiles – ideal portable wealth for a nomadic people – and their prowess as traders in everything from slaves to perfumes along the ancient Silk Road and across a region stretching from Constantinople to India.

The Chinese wanted their splendid horses, and in return the Sogdians got silk of exceptional quality. Some of their surviving textiles include three-metre silk panels used as tent hangings.

Their empire died out in the 10th century, and the shirt is dated to between the seventh and ninth centuries AD. The shirt, which was previously owned by a French collector, will be auctioned in the Arts of the Islamic world sale at Sotheby’s in London on 25 April.