Indo-Persian pigments detected in oldest surviving trade map

The world's oldest surviving merchant map - a 17th century 'Selden Map of China' which shows shipping routes reaching as far as India - may have been painted using Indo-Persian pigments and binders, scientists say.
The 1.6x1 metre map - which depicts ancient maritime trade routes in Asia - is thought to have been painted between 1607-1619 with watercolours and ink on Chinese paper.
It is a unique example of Chinese merchant cartography, showing a network of shipping routes with compass directions starting from the port of Quanzhou, Fujian province and reaching as far as Japan and India.
Researchers from Nottingham Trent University and Victoria and Albert Museum in the UK, using state-of-the-art imaging techniques, have for the first time been able to identify everything from the materials and techniques used to the mistakes and re-drawings made by the cartographer.

Researchers found the binding medium used for the map was gum Arabic, made from the sap of the acacia tree - typically used by European, south and west Asians - and not animal glue, which was almost always used in Chinese paintings at the time.
Examinations of the pigment used found a mixture of indigo with orpiment, a yellow mineral - rather than gamboge, a yellow dye - to make a green colour, which is also very unusual for a painting in China in this period.

The detection of a basic copper chloride in the green areas suggests an influence from south and west Asia, where it was often used in manuscripts. This green pigment was not typically used in paper-based paintings from China.

The binders and pigments used are more consistent with those found in manuscripts from a Persian or Indo-Persian tradition - and the Islamic world - than the European or Chinese, the researchers said.
The researchers have proposed that the map originated in Aceh, at the northwest end of Sumatra where it opens out to the Indian Ocean.
It is the most westerly port in south east Asia marked on the map and has the longest history of the presence of Islam in south east Asia, and a long history of Chinese contact.
It is also one of only six ports on the map marked with a red circle - possibly indicating the main trading network of the map's owner - and is the only port marked on the map to have a magnetic declination in the early 17th Century closest to that indicated by the tilt of the map's compass rose.

"This study illustrates the importance of not judging a book by its cover," said Professor Haida Liang from Nottingham Trent University.
"It is stylistically a Chinese painting that follows some Chinese and non-Chinese cartographic elements, but the painting materials and their usage are more akin to those of Persian or Indo-Persian manuscripts," she said.
"Because of its geographic location, Aceh was frequented by Indian, Arab, Chinese and European traders. We believe the map could have been made there by a Fujianese, possibly a Muslim in close contact with the Islamic world," she added.
The study was published in the journal Heritage Science.