Qatar population was 2.6 million: 313,000 Qatari citizens and 2.3 million expatriates. Islam is the official religion of Qatar. The country has the highest per capita income in the world. Qatar is classified by the UN as a country of very high human development and is widely regarded as the most advanced Arab state for human development. Qatar is a high-income economy, backed by the world's third-largest natural gas reserves and oil reserves. Qatar has been ruled by the House of Thani since Mohammed bin Thani signed a treaty with the British in 1868 that recognised its separate status. Following Ottoman
Udon Thani heavy rain and somewhat cooler temperatures during the day, although nights remain warm. The range of reliably recorded temperatures in the city is from to . The city alone has 399,535 inhabitants of the 1,572,786 for the province. In the mid-1900s, about 46,700 Vietnamese war refugees migrated to Udon Thani. Their descendants still reside in Udon Thani. Today, Udon Thani has the largest Vietnamese community in all of Thailand. By air: Udon Thani International Airport, close to the city centre (within the ring road), serves a number of domestic airports: Chiang Mai International Airport; U-Tapao International Airport (Pattaya); and Bangkok