"The Silurian is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at 443.8 million years ago, to the beginning of the Devonian Period, 419.2 Mya.<span> <span>Wikipedia."
https://www.google.com/search?q=He+Silurian+period+occurred&rlz=1C1RUCY_enUS760US760&oq=He+Silurian+...
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Answer:
sea trade
Explanation:
The control of sea trade, the chief source of Portuguese wealth in the East, was assured by the defeat of Muslim naval forces off Diu in 1509.
Portugal's main natural resources include fish, forests (cork), iron ore, copper, zinc, tin, tungsten, silver, gold, uranium, marble, clay, gypsum, salt, arable land and hydropower.
I think it is <span>Eurasia</span>
