Why did spanish power and prosperity decline

Spanish power and prosperity declined after their defeat.

Through the 1600's, Spain's strength decreased. Then there were economic problems also brought the decline Treasures from the Americas led Spain to neglect farming and commerce.

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Spanish power and prosperity declined aafter the defeat of the spanish . Through the 1600's, Spain's strength decreased. ... Then there were economic problems also brought the decline Treasures from the Americas led Spain to neglect farming and commerce.

Spain also controlled large parts of Italy (including Naples, Sicily, Sardinia and Milan), and much of the southern Netherlands (Flanders) as well as Franche Comté (bordering east central France).

In 1580, Philip II successfully invaded Portugal, claiming to have inherited it along with its possessions in the East Indies and Brazil.  

This vast array of possessions was administered by viceroys, governors, the Council of the Indies, and various other officials created piecemeal as each territory was acquired.

b. germany and italy