Phitsanulok and the River Nan

The lands situated in the present-day Phitsanulok Province of Thailand were inhabited since the stone age, although the neolithic inhabitants of the region are not likely to have been the ancestors of the modern Thai people who reside there today. The earliest historical records relating to what is now Phitsanulok Province indicates that at a time prior to or during the 11th century, the present-day city of Phitsanulok was but a small strategic Khmer outpost known as Song Khwae. During the next century, in 1188, Nakhon Thai, located near the center of the present Phitsanulok Province, was established as the capital city of the Singhanavati Kingdom, an early city-state of Thailand. Later, during Thailand's Sukhothai Period, the city of Phitsanulok emerged as a major city in the east of the Sukhothai Kingdom, and the great temples of Wat Chula Manee, Wat Aranyik and Wat Chedi Yod Thong were constructed. In 1357, the renowned Wat Phra Sri Rattana Mahathat was erected, and the Ayutthaya Period witnessed the construction of several of the province's other chief temples. Phitsanulok served for 25 years as the capital city of the Ayutthaya Kingdom. In 1555, King Naresuan the Great was born in the city of Phitsanulok. Naresuan played a significant role in the history of Thailand, as he expanded the kingdom (then called Siam) to its greatest territorial extent, by conquering sizable portions of modern day Burma and Cambodia. In recent times, Phitsanulok Province has become an important agricultural center, part of the Bread Basket of Thailand, providing rice and other crops to consumers in Thailand and throughout the world. Extensive agricultural development over the last hundred years or so has spawned a modern infrastructure in the urban areas of the province, bringing with it an array of modern roads, universities, hospitals and other conveniences. Over the years, the Nan River and its tributaries have played a substantial role in the history and development of the region by providing a route for transportation, fertile soil for agriculture, and water for irrigation. The river waters have also served as a route for enemy invaders, and have been the source of periodic widespread flooding throughout the province.

http://en.wikipedia.org/wiki/History_of_Phitsanulok_Province