Sotheby’s forthcoming arts of the Islamic World sale is estimated to realise in excess of $18 million.

In 2007, the company witnessed sales of Islamic, and modern and contemporary Arab and Iranian art fetching more than £20 million.

This year’s Arts of the Islamic World Sale, to be held on April 9, will comprise more than 400 lots of rare and important works of art, including metalwork, manuscripts, weaponry, ceramics, textiles and paintings that span from the 7th century through to the 16th, 17th, 18th and 19th centuries, the company said in a statement.

The sale, which is expected to realise in excess of £9 million, is set to attract enormous interest from collectors and connoisseurs of Islamic Art across the globe.

The most important work in the upcoming sale will be the 14th-century gold and enamel Royal Belt Buckle (illustrated front page) from Al-Andalus, which was produced during the Nasrid period (AD 1230-1492) in Granada, Spain. The buckle, which is inscribed with ‘Glory to our lord, the Sultan’, is an extraordinary example of the art of the goldsmiths in 14th-century Islamic Spain. It is likely to fetch more than £600,000.

A fine group of sacred relics, including an Abbasid ka’ba key and some 22 holy cloths, will also be included in the auction. The ka’ba key is arguably one of the most powerful symbols of Islam and this is the only one known to remain in private hands. It is estimated at £400,000-500,000.

In the wake of the strong results achieved for the ten sacred curtains offered in Sotheby’s last Islamic Art auction in October 2007 – the majority of which sold for well in excess of their pre-sale high estimates – the forthcoming sale will present the largest group of sacred curtains to have appeared on the market to date.

The 14 sacred textiles, which together are estimated to realise in excess of £920,000, will be headlined by four curtains in particular, the most important being a magnificent Ottoman velvet, silk and metal thread calligraphic band (hizam) from the holy ka'ba at Mecca, which dates from the early 20th century and is estimated at £120,000-160,000.

The second most valuable of the group is an important 19th-century Ottoman curtain from the Tawassul at Medina, which carries an estimate of £100,000-500,000.

Two further significant pieces in the group include an Ottoman curtain from the door of the Ra’isiyah minaret of the mosque of the prophet Hajrat Al-Qabr Al-Nabawi Al-Sharif in Medina, which is highly decorative and includes the embroidered tughra and signature of Sultan Mahumud II (AH 1223-1255/AD) 1808-1838, and a curtain from the tomb of the prophet Hujrat Al-Qabr Al-Nabawi Al-Sharif in Medina. Both curtains are estimated at £80,000-120,000.

Highlighting the manuscripts in the sale will be the earliest dated copy of the highly influential astronomical manuscript by Nasir al-Din al-Tusi's, the Zij-i Ilkhani.

Copied by Muhammad Ibn Mahmoud Ibn Ahmad Al-Jundabi, Ilkhanid, Persia, the manuscript, dated 24th Shawwal A.H. 676/A.D. 1277, is a highly important document of the Kitab al-Zij al-Ilkhani, or the Zij-i Ilkhani as it is known.

Copied only four years after the death of the author and leading 13th-century Muslim philosopher-scientist Nasir al-Din al-Tusi, and a mere eight years after the original was completed in 1270.

Al-Tusi, a universal scholar, and perhaps the most prolific author of the Islamic world, is best known in the history of science for his recensions of early Arabic translations of Greek works on astronomy and mathematics, various independent documents on aspects of theoretical and practical astronomy and mathematics, and this manuscript, the Persian scientific manuscript, the Zij-i Ilkhani.

Highlighting the Arms, Armour and Militaria section of the sale – one of the largest ever offered in a sale of Islamic Art – will be an important blade which once belonged