What advantage did portugal have that let it begin exploration before other european nations?

I believe the answer is: Its Atlantic ports were not under the control of the Moors.

The atlantic ports were really crucial for European countries to access The American contient. Due to the invasion of the Moors, Other European countries beside portugal felt that conducting an Exploration Eastwards would be extremely costly. This is why Portugal have a head start to explore the continent before other European countries

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