Tibet is traditionally divided into 3 main regions: U-Tsang, Kham and Amdo. U-Tsang is considered the cultural heartland of Tibet and starting point of the Tibetan civilization. It lies entirely within most of the modern day Tibet Autonomous Region except Qamdo. U-Tsang was formed centuries ago when the separate kingdoms of U and Tsang were combined. Traditionally, U, encompassed the area in and around Lhasa and the Yarlung Valley. Tsang, made up the western regions of Tibet from Gyantse west. Being the political, religious, economic and cultural center of Tibet, its famous attractions are Potala Palace, Jokhang temple, Namtso Lake, Sera Monastery, Tashilhunpo Monastery, Samye Monastery, etc.