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Much European indigo from Asia arrived through ports in Portugal, the Netherlands, and England.Many indigo plantations were established by European powers in tropical climates.The powder was then mixed with various other substances to produce different shades of blue and purple.
Indigo plantations also thrived in the Virgin Islands.However, France and Germany outlawed imported indigo in the 16th century to protect the local woad dye industry.Indigo was the foundation of centuries-old textile traditions throughout West Africa.Indigo remained a rare commodity in Europe throughout the Middle Ages.A chemically identical dye derived from the woad plant (Isatis tinctoria) was used instead.
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Oxidation by exposure to air converts indoxyl to indigo.