What is the name of the small, oil-rich Islamic sultanate of insular Southeast Asia?

Brunei State.

Explanation:

Hello!

Brunei State is a small country located in the north of the island of Borneo. It borders to the north with the China Sea and to the east, south and west with Malaysia.

The territory of Brunei is distributed by two parts that have no connection to each other. The territory of Brunei is distributed by two parts that have no connection to each other. Its extension is approximately 5,770 km2.

The name of its capital city is Bandar Seri Begawan.

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