in this context, 'protection money' is the most suitable equivalent because the words after 'makes it clear for selecting the proper sense. these words that give us the clue are: 'قبل التحالف العماني البحريني
Thus إتاوة here mean 'protection money' ( Money which is usually paid by a country or part of a country to another country, which is usually more powerful than the payee country, mainly for protection.
All the best.

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Note added at 2 hrs (2009-07-14 23:54:56 GMT)
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Note: in my explanation above, the words 'إتاوة' should be added, thus the wording in the first two lines will be:
in this context, 'protection money' is the most suitable equivalent because the words after 'إتاوة' makes it clear ....