Wat Yai Chai Mongkhon (Wat Chai Yai Mongkol) dates from the reign of King U Thong (Uthong) and was built around 1357. U Thong or Ramathibodi I (13141369) was the first king of the kingdom Ayutthaya, reigning from 1351 to 1369. He was known as Prince U Thong before he ascended to the throne on March 4, 1351. A native of Chiang Saen (now in Chiang Rai Province) he claimed descent from Khun Borom and propagated Theravada Buddhism as the state religion. Ayutthaya (Ayudhya)) was a Siamese kingdom that existed from 1351 to 1767. Ayutthaya was friendly towards foreign traders, including the Chinese, Vietnamese (Annamese), Indians, Japanese and Persians, and later the Portuguese, Spanish, Dutch and French, permitting them to set up villages outside the city walls. In the sixteenth century, it was described by foreign traders as one of the biggest and wealthiest cities in the East. The court of King Narai (16561688) had strong links with that of King Louis XIV of France, whose ambassadors compared the city in size and wealth to Paris.