Tin mining was important in the Cornish economy from the High Middle Ages, and expanded greatly in the 19th century when rich copper mines were also in production. In the mid-19th century, tin and copper mines entered a period of decline and china clay extraction became more important. Mining had virtually ended by the 1990s. Fishing and agriculture were the other important sectors of the economy, but railways led to a growth of tourism in the 20th century after the decline of the mining and fishing industries.