The federation’s economy is dominated by the petroleum produced primarily in the Abu Dhabi emirate. The wealthiest of the emirates, Abu Dhabi contains one of the largest concentrations of the world’s proven oil reserves and contributes a significant portion of the national budget. The emirate of Dubai, whose economy is centred more on business than on oil, serves as a commercial and financial hub for the region and leads the country in economic diversification.
Source: britannica.com