Prussian blue was imported to Japan in the 1820s.

Evidence

Prussian blue was imported either directly by Dutch traders or, more probably, via China, where it was being manufactured from the 1820s. — Neil MacGregor, A History of the World in 100 Objects, 1420

Categorization

• corroborated: 2 independent passages support this claim — Neil MacGregor, A History of the World in 100 Objects, 1420