500 years before Buddha Sakyamuni came into this land i.e., circa 1063 B.C., a semi-legendary figure known as Lord Shenrab Miwo reformed the primitive animism of the Shen race and founded the Tibetan Bonpo religion. According to Bonpo religion sources there were eighteen Shangshung Kings who ruled Tibet before King Nyatri Tsenpo. Tiwor Sergyi Jhagruchen was the first Shangshung King in Tibet.Shangshung, before its decline, was the name of an empire which comprised the whole of high Himalayan kingdom Tibet.
Before Shangshung empire declined, a kingdom known as Bod, the name of Tibet, came into existence at Yarlung and Chongyas valleys at that time of King Nyatri Tsenpo, who started the heroic age of the Religious Kings. The Tibetan Royal Year of the modern Tibetan calendar is dated from the enthronement of King Nyatri Tsenpo in 127 B.C.