Sikkim was inhabited in pre-historic times by three tribes namely Naong, Chang and the Mon. The Lepcha who entered Sikkim sometimes later absorbed them completely. The origin of Lepchas is shrouded in mistery but it seems that they belonged to the clan of the Nagas of the Mikir, Garo and Khasia hills which lie to the south of the Bramaputra valley. Some believe they came from somewhere on the borders of Tibet and Burma. According to their own tradition they came to Sikkim from the east in company with Jindaxs, who went to Nepal and shared their tradition. The Lepchas were a very peace loving people, deeply religious and shy, which characteristics they still have retained. They were in fact the children of nature, and worshipped nature or spirits of nature. These Lepcha lived quite close to the nature by way of leading sustenance. Some of them practiced shifting cultivation and raised grains like maize and millets. They led a tribal life at the beck and call of their tribal leader.

The credit of organizing them into some sort of a society goes to a person called Tur ve pa no. He was eventually elected leader of king called "Punu" sometimes in A. D. 1400. He was killed in a battle and was succeeded by three Kings - Tur Song Pa No, Tur Aeng Pa No and Tur Alu Pa No. The monarchy came to an end with the death of the last king. The Lepchas now resorted to the practice of electing a leader whose advice and counsel was sought on crucial matters and followed. The Tibetan migration in early 17th century led the Rongs to shift their habitats so as to avoid conflict. Meanwhile the struggle and conflicts among the followers of the "Yellow hats" and the "Red hats" in Tibet forced the latter to seek refuge in Sikkim, where they attained the status of aristocracy. Being aggressive they occupied lands, which was not registered by the docile Lepchas. These Tibetan migrants (the Bhutias as they came to be known) who were followers of the sect of 'Red Hats' now tried to convert these Sikkimese "Worshippers of nature" to Buddhism. They succeeded to some extent, though the Lepchas tried to keep themselves aloof as far as possible. In order to avoid any possible opposition from the Lepchas, these immigrants now chose one venerable person Phuntsok Namgyal as the temporal and spiritual leader of Sikkim, whose ancestry they traced from a legendary prince, who founded the Kingdom of Minvang in eastern Tibet in 9th century A.D. This dynasty ruled in the Chumbi and Teesta valley for a long time.

Somewhere in the Thirteenth century a prince named Guru Tashi of Minyang dynasty in Tibet had a divine vision that he should go south to seek his fortune in "Denzong- the valley of rice". As directed by the divine vision he along with his family, which included five sons, headed in the southern direction. The family during their wandering came across the Sakya Kingdom in which a monastery was being built at that time. The workers had not been successful in erecting pillars for the monastery. The elder son of Guru Tashi raised the pillar single handedly and thereby came to be known as "Kheye Bumsa" meaning the superior of ten thousand heroes.

The Sakya King offered his daughter in marriage to Khye Bumsa. Guru Tashi subsequently died and Khye Bumsa settled in Chumbi Valley and it was here that he established contacts with the Lepcha Chieftain Thekong Tek in Gangtok. Khye Bumsa being issueless went to Sikkim in the 13th century to seek the blessing of Thekong Tek who was also a religious leader. Khye Bumsa was not only blessed with three sons by the Rong chief but he also prophesied that his successors would be the rulers of Sikkim. Out of gratitude Khye Bumsa visited Thekong Tek a number of times. In due course of times the relationship ultimately culminated in a treaty of brotherhood between the two Chieftains at a place called Kabi Longtsok. This treaty brought about new ties of brotherhood between the Lepchas and the Bhutias.

Mipon Rab the third son of Khye Bumsa assumed the Chief-Ship after the death of his father. He had sons and the four principal clans of Sikkim are said to have sprung from these four sons. The fourth son Guru Tashi succeeded Mipon Rab and shifted to Gangtok. On the other hand after the death of Thekong Tek the Lepchas broke into minor clans. They also gradually turned to Guru Tashi for protection and leadership. Guru Tashi appointed a Lepcha, Sambre as his chief adviser and lieutenant. Guru Tashi's rule marked the absorption of the foreign ruling house into the native soil and also paved a way for a regular monarchy. This way Guru Tashi became the first ruler of Sikkim and was crowned as such. He was followed by Jowo Nagpo, Jowo Apha and Guru Tenzing who pursued the policy creating progressively amicable relation with Lepchas.

Phuntsok (or penchu) Namgyal was the next ruler. He was Guru Tenzing's son (great grandson of Guru Tashi) and was born in 1604. Phuntsok Namgyal's crowning was charged with all the vivid fantacy and miraculous phenomenon that is befitting to so important an occasion. Three venerable lamas are said to have entered sikkim from three different direction direction at the same time. They met at Yoksam (meaning three wise men) and began a debate on the desirability of having a temporal and religious head to rule over pagan Sikkim. Two of the lamas furthered their own claims but the third lama reminded them of the prophecy of Guru Padamsambhava that a man coming from east and Phuntsok by name would rule Sikkim. It was also told that none of them came from east hence the real man must be looked for. Messengers were sent to seek Phuntsok. Near Gangtok the desired youngman was found and lamas lost no time in crowning him the king. They seated him on a nearby rock slab and sprinkled water on him from the sacred urn. He was given one of Lhatsun Chenpo's (the lama told about prophecy) names, Namgyal, and the title of Chogyal or religious king. It happened in the year 1642. The Namgyal dynasty ruled over Sikkim as hereditary kings for about 332 years.’

Phuntsok Namgyal, the first consecrated ruler ruled over a vast territory, many times the size of present Sikkim. His kingdom touched Thang La in the Tibet in the north, Tagong La near Paro in Bhutan in the east and the Titalia on the borders of West Bengal and Bihar in the south. The western border Timar Chorten on the Timar river in Nepal. Phuntsok though a distant descendant of Indrabodhi was now a Bhutia by his domicile. He was persuaded by the lamas enthroning him as Chogyal (Heavenly king or king who rules with righteousness) to seek recognition from Dalai Lama of Tibet. The Dalai Lama recognized Phuntsok Namgyal as the ruler of the southern slopes of the Himalayas (Sikkim) and is also credited to have sent ceremonial present such as the silken scarf bearing Dalai Lama's seal, the mitre(hat) of the Guru Rimpoche, the devil dagger (Phurpa) and the most precious sand image of the Guru. Consequently, the newly established Bhutia principality of Namgyal Dynasty was tied to Tibetan theocracy. Since then up to 19th century, the Bhutia rulers of Sikkim looked up to Tibet for protection against political foes. Phuntsok Namgyal proved to be an efficient and capable administrator. He divided his kingdom into twelve Dzongs i.e. districts and appointed Dzongpana i.e. governor for each. He also declared Mahayana Buddhism as the state religion, which continued to be the state religion under all the Namgyal rulers. He very tactfully kept the lepchas, Bhutias and Limbus together. The Governors were appointed from the lepchas who were then in majority. Since Yatung the greatest commercial Tibetan center being nearer to Gangtok posed some danger, he shifted his capital to Yoksom.

Phunstok Namgyal and the three saints immediately got to the task of successfully bringing the Lepcha tribes under the Buddhist fold. Politically, sikkim expanded its borders, which include Chumbi valley, the present Darjeeling district and a part of present-day Nepal and Bhutan. The capital of sikkim was established in Yoksam itself.

Tensung Namgyal succeded his father Phuntsok Namgyal in 1670 and moved his capital to Rabdentse. He had three wives - a Tibetan, a Bhutanese and Limbu girl. The latter was the daughter of the Limbu chief Yo Yo-Hang. The chief's daughter brought with her seven girls who were later on married into important families of Sikkim. Many of them rose to the rank of councilors to the King. These councilors later on came to be known as Kazis who enjoyed immense power and privileges.

Chador Namgyal a minor son from Tensung's second wife succeeded on the death of his father. Pedi the daughter from the first wife who came from Bhutan challenged the succession and invited Bhutanese intervention. Having come to know about this secret move Yungthing Yeshe a loyal minister took the minor king to Lhasa. During his asylum in Lhasa, Chador Namgyal distinguished himself in Buddhist learning and Tibetan literature. By dint of his acumen and scholarship he rose to the position of state astrologer to the Sixth Dalai Lama. The Dalai Lama was so much pleased with the erudition of this young scholar that he bestowed high honors and titles on the young king. The young king also received an estate in central Tibet with sovereign rights. On the other hand Bhutanese forces had captured the Rabdentse palace and imprisoned the son of Yugthing Yeshe. But on the intervention of Tibet, King Deb of Bhutan withdrew. Chador Namgyal came back and drove out the rest of Bhutanese forces. The south-eastern tract was, however, lost to sikkim as it had been heavily colonized by then. The Bhutanese after a short while made a second attempt to capture Sikkim territory. Chador Namgyal gave a tough resistance but areas now called as Kalimpong and Rhenock were lost forever. Chador was himself religious and took steps for the propagation of Buddhist religion in his territory. He commanded that the second of every three sons of Bhutia family must be ordained a monk of the Pemiongchi Monastery, which was also open to the Tsongs. He not only built the Guru Lhakhang Tashiding (1715) and patronised the sacred places but also adapted the religious dances (mystery plays) to keep alive the martial and native traditions and invented an alphabet for the Lepchas. However, Pedi the half sister of the ruler did not reconcile. She conspired with a Tibetan man of medicine and caused Chador Namgyal's death by way of blood letting from a main artery while the king was holidaying at Ralang hot water spring in 1716. A force was sent to Namchi, the doctor was executed and Pedi was strangled to death by a silk scarf.

Gyurmed Namgyal succeeded his father Chador. Consequently upon a Mongol (Dzungar) invasion on Tibet to persecute Nyingma sect, the Mindoling Abbot's sister. In his times the people were forced to work on the fortification of Rabdentse in the fear of Gurkhas and Bhutanese raids. Many Tsongs who were not prepared to yield to forced labour fled to Limbuana, which became a rebel district and broke away from Sikkim even earlier to Gurkha expansion. A boundary dispute with Bhutan also arose. The Magar Chieftain Tashi Bidur also revolted, though he was subdued. Limbuana was, however, lost to Nepal. Gyurmed had no issue but while on his death bed at the age of 26 (1733) gave out that a nun in Sanga Choling was carrying his child. But some people do not believe it. It is said, he was impotent and generally shunned his wife.

Therefore, the story goes that in order to keep the Namgyal Dynasty going, the lama priest of Sikkim concocted a story that a nun was carrying the child of the King. Fortunately the nun delivered a male child and he was accepted as heir to Gyurmed. He was named as Phuntsok after the first temporal and the spiritual head of Sikkim.

Phuntsok Namgyal II was opposed by many people including some Bhutias on the plea of illegitimacy. Tamdang a close confident and treasurer of Gyurmed not only opposed the succession but assured the powers of the ruler and continued to rule Sikkim for three years inspite of the opposition by pro-king faction. The Lepchas backed the baby king and fought the pretender under the leadership of Chandzod Karwang. Tamdang was defeated and fled to Tibet to seek guidance and help. But to keep Sikkim under their Tutelage the Tibetan authorities favoured the minority of the king. A convention representing all shades of Sikkimese population was held which defined the functions, powers and responsibilities of the Government. The system of annual taxation was also introduced to augment the state treasury. The Magar tribe, lost its chieftain during this time and asked the regent to appoint the deceased's son as chieftain. But the regent expressed his inability to comply with their demand. This act enraged the Magars who sought the help and protection from Bhutan. This way Sikkim lost Magars allegiance forever. In the year 1752 the Tsongs rose in arms, but were subdued and won over by tactfully by Chandzod Karwang. The rise of Gurkhas also posed a threat for Sikkim. The later years of Phuntsok II witnessed Gurkhas inroads in Sikkim under the leadership of Raja Prithvi Narayan Shah of Nepal who formented the rebellious elements in Sikkim. Bhutan also invaded Sikkim and captured all area east of Tista, but withdrew to present frontiers after negotiation at Rhenock. The Gurkha inroads were beaten back seventeen times. A peace treaty with Nepal was signed in 1775, and Gurkhas promised to abstain from further attacks and collaboration with Bhutanese. But the Gurkhas at a later stage violated the treaty and occupied the land in western Sikkim. Phuntsok II had three queens but had a son Tenzing Namgyal from his second queen in 1769.

Tenzing Namgyal succeeded Phuntsok Namgyal in 1780. During the reign of Tenzing Namgyal, Nepali forces occupied large chunks of Sikkim territory. They attacked Rabdantse and the Chogyal had to flee to Tibet. The Nepalis excursions emboldened them to penetrate even into Tibet. This led to the Chinese intervention and Nepal was defeated. In the Sino-Nepal treaty, Sikkim lost some of its land to Nepal, but monarchy was allowed to be restored in the country. Tenzing Namgyal died in Lhasa and his son Tsudphud Namgyal was sent to Sikkim in 1793 to succeed him as the monarch. Rabdantse was now, considered too insecure because of its proximity to the Nepal border and Tshudphund Namgyal shifted the capital to a place called Tumlong.

The defeat of Nepal by the Chinese did little to weaken the expansionist designs of the Nepalese. They continued to make attacks into the neighbouring British territories and Sikkim. British India successfully befriended Sikkim. They felt that by doing so the expanding powers of the Gorkhas would be curtailed. British also looked forward to establishing trade link with Tibet and it was felt that the route through Sikkim was the most feasible one. War between Nepal and British India broke out in 1814 and came to an end in 1816 with the defeat of the Nepalis and the subsequent signing of the Treaty of Sugauli. As a direct spin-off, British India signed another treaty with Sikkim in 1817 known as the Treaty of Titalia in which former territories, which the Nepalis captured, were restored to Sikkim. H. H. Risley writes in the Gazette of Sikkim, 1894, that by the Treaty of Titalia British India has assumed the position of Lord's paramount of Sikkim and a title to exercise a predominant influence in that State has remained undisputed.

The British became interested in Darjeeling both as a hill resort and an outpost from where Tibet and Sikkim would be easily accessible. Following a lot of pressure from the British, Sikkim finally gifted Darjeeling to British India on the understanding that a certain amount would be paid as annual subsidy to Sikkim. The gift deed was signed by the Chogyal Tsudphud Namgyal in 1835. The British appointed a superintendent in the ceded territory. The British however did not pay the compensation as had been stipulated and this led to a quick deterioration of relation between the two countries. There were also difference between the British Government and Sikkim over the status of people of Sikkim. Because of the increased importance of Darjeeling, many citizens of Sikkim mostly of the labor class started to settle there as British subjects. The migration disturbed the feudal lords in Sikkim who resorted to forcibly getting the migrants back to Sikkim. This annoyed the British Government, which considered these as acts of kidnapping of British citizens. The relations deteriorated to such an extent that when Dr. Campbell, the Superintendent of Darjeeling and Dr. Hooker visited Sikkim in connection with the latter's botanical research, they were captured and imprisoned in 1849. The British issued an ultimatum and the two captives were released after a month of detention. In February 1850, an expedition was sent to Sikkim, which resulted in the stoppage of the annual grant of Rs. 6000/- to the Maharaja of Sikkim and also the annexation of Darjeeling and a great portion of Sikkim to British India.

Sikkim resorted to making attacks into British territories and it was in November 1860 that the British sent an expeditionary force to Sikkim. This force was driven back from Rinchenpong in Sikkim. A stronger force was sent in 1861 that resulted in the capture of the capital Tumlong and the signing of a Treaty between the British and Sikkimese the same year.

His son Sidekeong Namgyal succeeded Tsugphud Namgyal in 1863. The British Government started the payment of annual subsidy of Rs. 6000/- in 1850 for Darjeeling. In an attempt to keep good relation with Sikkim, the British enhanced the subsidy to Rs. 12000/- per annum.

Chogyal Sidekong Namgyal defied in 1874 issueless and was succeeded by his half brother Thutob Namgyal. There were serious difference between the Nepalese settlers and the original inhabitants of Sikkim and this led to British intervention. The settlement went in favour of the Nepali settlers and made Thutob Namgyal have ill feeling for the British. He retreated to Chumbi and became more aligned towards the Tibetans.
The British meanwhile were making concerted efforts to establish a trade links with Tibet and also imposed their influence. A delegation led by Colman Macaulay, Financial Secretary to the Bengal Government of British India was sent to Sikkim in 1884 to explore the possibility of establishing a trade route with Tibet through the Lachen Valley. This delegation visited Tumlong the capital where it met the Maharaja.

The Britishers started building of roads in Sikkim. This was viewed with suspicion by Tibet and in 1886, some Tibetan militia occupied Lingtu in sikkim near Jelepla pass. In May 1888, the Tibetans attacked Gnathang below Jelepla but were driven away. In September of the same year the British called for reinforcements and the Tibetans were pushed back from Lingtu. A memorial was built at Gnathang for the few British soldiers who died in the engagement.
The Britishers appointed Claude White as the first political officer in Sikkim in 1889 and Chogyal Thutob Namgyal was virtually under his supervision. Thutob Namgyal shifted the capital from Tumlong to Gangtok in 1894. The Sir Thutob Namgyal Memorial (STNM) Hospital built in 1917 is named in the memory of Thutob Namgyal who died in 1914.

Alarmed by the growing Russian influence in Tibet and also to assert itself, the British sent an expedition led by Col. Younghusband to Lhasa via Jelepla in 1904. The expedition met with resistance from the Tibetan army, which was defeated, and a treaty was dictated by Younghusband on Tibet. The Treaty secured monopoly-trading privileges in Tibet for the British. Thutob Namgyal was succeeded by his son Sidekong Tulku in 1914. Unfortunately he did not live long and died in the same year. He was succeeded by his half brother Tashi Namgyal who promulgated many reforms in the state.

In 1947 when India became independent, Tashi Namgyal was successful in getting a special status of protectorate for Sikkim. This was in face of stiff resistance from local parties like Sikkim State Congress who wanted a democratic setup and accession of Sikkim to the Union of India.

The treaty signed between India and Sikkim ratified the status of Sikkim as a protectorate with Chogyal as the Monarch. Tashi Namgyal died in 1963 and was succeeded by his son Palden Thondup Namgyal. By the beginning of 1970 there were rumbling in the political ranks and file of the State, which demanded the removal of Monarchy and the establishment of a democratic setup. This finally culminated in wide spread agitation against Sikkim Durbar in 1973.There was a complete collapse in the administration. The Indian Government tried to bring about a semblence of order in the state by appointing a Chief administrator Mr. B. S. Das. Further events and election led to Sikkim becoming transformed from a protectorate to an associate State. On 4th September 1947, the leader of Sikkim Congress, Kazi Lendup Dorji was elected as the Chief Minister of the state. The Chogyal however still remained as the constitutional figure head monarch in the new setup. Mr. B. B. Lal was the first Governor of Sikkim.

Events leading to the confrontation between the Chogyal and the popular Government caused Sikkim to become a full-fledged 22nd state of the Indian Union on 16th may 1975. The institution of Chogyal was subsequently abolished.

Since then Sikkim has been a state of the Indian Union like any other state. The 1979 assembly election saw Mr. Nar Bahadur Bhandari being elected as the Chief Minister of Sikkim. He has been returned to office in the election held in 1984 and 1989. In 1994 assembly election

Mr. Pawan Kumar Chamling became the fifth Chief Minister of Sikkim.