A woman works at a factory producing clay pots at Phu Lang pottery village in Bac Ninh province, Vietnam, May 14, 2015. The village is part of an old pottery triangle in northern Vietnam which includes Bat Trang and Tho Ha, and has been producing pottery since the 13th century, according to local media. (Photo by Reuters/Kham)

A woman works at a factory producing clay pots at Phu Lang pottery village in Bac Ninh province, Vietnam, May 14, 2015. (Photo by Reuters/Kham)

Workers dry products at a factory producing clay pots at Phu Lang pottery village in Bac Ninh province, Vietnam, May 14, 2015. (Photo by Reuters/Kham)

Women paint pottery jars at a factory at Phu Lang pottery village in Bac Ninh province, Vietnam, May 14, 2015. (Photo by Reuters/Kham)

Workers put clay products to dry at a factory at Phu Lang pottery village in Bac Ninh province, Vietnam, May 14, 2015. (Photo by Reuters/Kham)

A man puts clay products to dry at a factory at Phu Lang pottery village in Bac Ninh province, Vietnam, May 14, 2015. (Photo by Reuters/Kham)

A woman makes a clay pot at a factory at Phu Lang pottery village in Bac Ninh province, Vietnam, May 14, 2015. (Photo by Reuters/Kham)

A woman puts clay products to dry at a factory at Phu Lang pottery village in Bac Ninh province, Vietnam, May 14, 2015. (Photo by Reuters/Kham)

Clay pots and lids are left to dry at Phu Lang pottery village in Bac Ninh province, Vietnam, May 14, 2015. (Photo by Reuters/Kham)

A woman makes clay lids at a factory at Phu Lang pottery village in Bac Ninh province, Vietnam, May 14, 2015. (Photo by Reuters/Kham)

A woman puts clay pots and lids to dry at Phu Lang pottery village in Bac Ninh province, Vietnam, May 14, 2015. (Photo by Reuters/Kham)