The Persian Gulf is particularly well-endowed with this strategic raw material: five Persian Gulf states, Saudi Arabia, Iraq, the UAE, Kuwait, and Qatar, are among the top ten petroleum or gas exporters worldwide. In Africa, Algeria (10th world) and Libya are important gas exporters. In addition Bahrain, Egypt, Tunisia, and Sudan all have smaller but significant reserves. Where present, these have had significant effects on regional politics, often enabling rentier states, leading to economic disparities between oil-rich and oil-poor countries, and, particularly in the more sparsely populated states of the Persian Gulf and Libya, triggering extensive labor immigration. It is believed that the Arab world holds approximately 46% of the world's total proven oil reserves and a quarter of the world's natural-gas reserves.