Woad was the primary blue dye of Europe for over 2,000 years — from ancient Celtic times through the medieval period. The Languedoc region of France (Toulouse, Albi, Carcassonne) built extraordinary wealth on woad cultivation in the 14th–15th centuries — the "pays de cocagne" (land of plenty) owes its name to the woad industry (cocagne = woad ball). The arrival of tropical indigo in Europe destroyed the woad industry within decades.

Ancient, earthy, and atmospheric. Woad blue is a softer, less precise blue than indigo — it has the quality of something made from the land, variable and organic. Associated with Celtic identity, ancient warrior culture, and the particular blue of northern European landscapes.

Julius Caesar's account of blue-painted Britons established the cultural association of woad with Celtic resistance to Roman conquest. This association — however historically uncertain — made woad blue a symbol of Celtic identity and defiance. The Braveheart (1995) film's use of blue face paint (though historically inaccurate for the period depicted) reinforced this mythology in popular culture. The woad industry's destruction by imported indigo is one of history's clearest examples of colonial trade disrupting indigenous industries.