Phuntsog Namgyal, the first Chogyal or King of Sikkim, was consecrated as king of Sikkim at Yuksom and succeeded by his son, Tensung Namgyal in 1670. The reign of the Chogyal was peaceful and saw the capital shifted from Yuksom to Rabdentse. The Namgyal had three wives – a Tibetan, a Bhutanese and a Limbu girl. The Limbu girl, daughter of the Limbu chief Yo Yo-Hang had inducted seven girls from her family who all married into noble Sikkim families. Many of them became councillors to the King and were given the title Kazi, which gave them enormous powers and privileges.
The king's second wife's son Chador Namgyal, took over the reins of power in Sikkim, after his father’s death, in 1700. He was a minor at that time. This outraged his elder half-sister Pendiongmu (daughter of first wife of Tensung Namgyal), of Bhutanese descent, who opposed the succession and with help from Bhutan evicted Chador. Chador fled to Tibet (Yungthing Yeshe, a loyal Minister escorted the minor king to Lhasa) where he remained in exile for ten years before returning and reclaiming his lost territory with the help of the Tibetans.
While in Lhasa, Chador Namgyal became very proficient in Buddhism and Tibetan literature, and also became the state astrologer to the Sixth Dalai Lama. During his exile, the Sixth Dalai Lama pleased with the erudition of Chador Namgyal had conferred on him exclusive rights to an estate in Tibet. During this period, the son of Yugthing Yeshe (who had saved Chador and taken him to Tibet) was imprisoned by the Bhutanese in Rabdentse. Tibet intervened in the matter and also prevailed on King Deb of Bhutan to withdraw from Sikkim. Chador Namgyal then returned to Rebdantse and the small forces of Bhutan which remained were forced to withdraw. During this period, Sikkim lost some areas in its south-eastern region since Bhutan had colonized the area.
Pedi, the Chogyal’s half sister, had not given up on her enmity against her half brother Chador. With the help of a medicinal man from Tibet she got Chador Namgyal murdered in 1716 through a mysterious blood letting from a main artery while the king was on a holiday at the Ralang hot water spring. Immediately, the royal armed forces executed the Tibetan doctor and also put Pedi to death by strangling her with a silk scarf.
Gurmed Namgyal succeeded his father Chadok in 1717. Gurmed's reign saw many skirmishes between the Nepalese and Sikkimese. He had Rabdentse fortified to prevent invasions by the Gurkhas (Nepalese) and Bhutanese. In addition, a local Magar chieftain Tashi Bidur had also rebelled, but was subdued. Gurmed died in 1733 at a young age of 26. Since he did not have any legitimate children, on his death bed he conveyed that a nun at Sanga Cheoling was carrying his child (this is said to be the story concocted by the Lamas to perpetuate the Namgyal Dynasty). Subsequently, the nun gave birth to a male child who was accepted as heir to Gurmed and was given the name Phuntsog, after the first temporal and the spiritual head of Sikkim.
Phunstog Namgyal II, the illegitimate child of Gurmed, succeeded his father to the throne in 1733. His reign was tumultuous as he was faced with attacks by the Bhutanese and the Nepalese, apart from rebellions within Sikkim from Magars and the Tsongs in 1752. Since Namgyal II was a weak king, the Nepalese had made 17 invasions against Sikkim. Bhutan had also attacked Sikkim and occupied areas east of Tista River; however, they later withdrew to present frontiers after negotiations held at Rhenock.
Tenzing Namgyal, the next king was also a weak ruler, and his sovereignty saw most of Sikkim being appropriated by Nepal. The Chogyal was forced to flee from Rabdentse to Lhasa where he died in 1780. Tshudpud Namgyal, his son returned to Sikkim in 1793 to reclaim the throne with the help of China. Finding Rabdentse too close to the Nepalese border, he shifted the capital to Tumlong. Consequent to the repeated attacks by the Bhutanese and Nepalese over the many invasions, the capital city was reduced to ruins by the liberating army of Nepal.