Vientiane Prefecture (Lao: ນະຄອນຫຼວງວຽງຈັນ, Nakhônlouang ViangChan) is a prefecture of Laos, in the northwest Laos. The national capital, Vientiane, is in the prefecture. The prefecture was created in 1989, when it was split off from Vientiane province. On a curve of the Mekong River, and bordering Thailand, the prefecture covers an area of . Vientiane city was built in the 16th century in the reign of King Saysethathirath. The older part of the city has ancient temples, museums, monuments and parks. Protected areas in the prefecture include Phou Khao Khouay National Protected Area, Phou Phanang National Protected Area, and Houay Ngang Forest Reserve, a good area for bird and butterfly watching. The prefecture is the site of the First Thai–Lao Friendship Bridge spanning the Mekong to connect with Nong Khai Province, Thailand and the New Laos National Stadium open 2009 at Route 13. The Laotian epic, the Phra Lak Phra Lam, claims that Prince Thattaradtha founded the city when he left the legendary Lao kingdom of Muong Inthapatha Maha Nakhone because he was denied the throne in favor of his younger brother. Thattaradtha founded a city called Maha Thani Si Phan Phao on the west bank of the Mekong; this city was said to have later become today's Udon Thani, Thailand. One day, a seven-headed Naga told Thattaradtha to start a new city on the east bank of the river opposite Maha Thani Si Phan Phao. The prince called this city Chanthabuly Si Sattanakhanahud, which was said to be the predecessor of modern Vientiane. Contrary to the Phra Lak Phra Ram, most historians believe that the city of Vientiane was an early Khmer settlement centered around a Hindu temple, which the Pha That Luang would later replace. Khmer princes ruling Say Fong were known to have made pilgrimages to the shrine near Vientiane. In the 11th and 12th centuries, the time when the Lao and Thai people are believed to have entered Southeast Asia from southern China, the few remaining Khmer in the area were either killed, removed, or assimilated into the Lao civilization, which would soon overtake the area.