A medieval chess piece found in a Scottish antique dealer's drawer has been sold at auction for 735,000 pounds ($1.3 million).

Key points: The Lewis Chessmen were first discovered in 1831

The Lewis Chessmen were first discovered in 1831 The piece belonging to the set was stored in a drawer for years

The piece belonging to the set was stored in a drawer for years Other pieces are held in the British Museum in London and the National Museum of Scotland

The 900-year-old Lewis Chessmen piece was considered among the greatest artefacts of the Viking era, and was initially expected to bring between 600,000 pounds and 1 million pounds ($1.8 million) at Sotheby's auction house.

The piece was bought for just five pounds in 1964. It was passed down to the family of the unnamed Scottish antiques dealer, who did not realise its significance until it was evaluated.

The Lewis Chessmen are a hoard of 93 pieces in the form of Norse warriors, including shield-chewing berserkers, carved from walrus ivory in the 12th century.

They were discovered in 1831, buried in a sand dune on Scotland's remote Isle of Lewis.

The pieces are held in the British Museum in London and the National Museum of Scotland in Edinburgh, but five of them have been missing — until last month.

The newly discovered piece is 8.8 centimetres tall and the equivalent of a rook.

The Lewis Chessmen pieces are carved from walrus ivory, and believed to have been made in Norway c. 1150–1175 CE. ( Trustees of the British Museum )

Kept in drawer 'for many years'

In a statement, a family spokesman said the dealer had bought it in 1964 from another Edinburgh dealer.

"It was catalogued in his purchase ledger that he had bought an 'Antique Walrus Tusk Warrior Chessman'," the spokesman said.

"From this description it can be assumed that he was unaware he had purchased an important historic artefact.

"It was stored away in his home, and then when my grandfather died my mother inherited the chess piece.

"For many years it resided in a drawer in her home, where it had been carefully wrapped in a small bag. From time to time, she would remove the chess piece from the drawer in order to appreciate its uniqueness."

The long-lost piece was sold at the Sotheby's auction house for 735,000 pounds ($1.3 million). ( AP: Tristan Fewings/ Sotheby's )

ABC/AP