The year 1642 holds a important place in history of the region, as it was the year, when the first Chogyal (ruler/King) of Sikkim, Phuntshog Namgyal was enthroned and the Kingdom of Sikkim was established. But, the establishment of a Bhutia kingdom towards the east did not suit well with the ethnic Mangars and Limbus of the present day. A war broke out with the newly established kingdom.
The king – Phuntshog Namgyal realizing that it would be difficult for a newly formed kingdom to sustain a prolonged war, sought for, and won truce with the ethnic tribes of the region, which led to the signing of a pact called Lho-mon-tsong-sum (lho-Bhutias, mon-Lepchas, tsong-Limbus, and sum-three), thus laying the foundation for the Bhutia-Lepcha-Limbu trinity. What's most significant to note here is that the Limbus and the Mangars, who now constitute a large part of the "Gorkhali" population demanding Gorkhaland were living in the region even before the formation of the Kingdom of Sikkim.
The next important year in the history of the region was 1707, by then Bhutan had already conquered and retreated from most kingdom of Sikkim, other than the lands to the east of river Teesta – what we today know as Kalimpong. By the year 1750s, the Gorkhalis in the west had become emboldened and they had started to attack the kingdom of Sikkim with impunity and in 1777 they had appropriated the Kingdom of Sikkim, which forced the then Chogyal Tenzing Namgyal to flee from his capital Rabdentse to Lhasa where he eventually died in 1780. The Chogyal’s son tried to regain his kingdom with the help from his Tibetan supporters but was defeated, subsequent wars led to the ruining of the capital of ancient Sikkim – Rabdentse and the ruins of which can still be seen near Pelling in Sikkim.
This is an important juncture in the history of the region, as it clearly shows that the Gorkhalis had in fact conquered the present day Darjeeling region and just like any conquering forces, the Gorkhali population began to grow in the region with passing of time. The Gorkhali presence as being ethnic to the region has already been proven in the form of Mangars and the Limbus and to say that the rest of the Gorkhalis are/were immigrants in the region would be akin to calling the Mughals and hence the entire Muslim population of India to be immigrants.
The year 1816 is yet another important date in its history. It was the year in which following a long series of battles, the Gorkhalis lost Kumaon, Garhwal and Sikkim (which included Darjeeling) and most of the terai region to the British through the Treaty of Sugauli. The British in turn handed the reigns of Sikkim once again to Chogyal but with some conditions, which in particular included a clause, which would give the British the right to interfere in the affairs of the Kingdom of Sikkim, thus a treaty to that effect was signed by both the parties and that treaty is today known as the Treaty of Titaliya – 1817.
One of the significant outcome of this treaty for Darjeeling is that the Chogyal of Sikkim allowed the British to use the area known as Dorje-Ling as sanatorium in the year 1835. Even though the Chogyal had only allowed the British to use the areas in and around what is today Darjeeling town, the British took the lands to the west of Teesta and the east of Mechi – the present day Darjeeling region for their use in return for a nominal tribute (Rs. 3000 per annum) to be paid by the British. By the year 1866, the British had annexed the present day of Kalimpong and Doors from Bhutan following the defeat of Bhutan in the Anglo-Bhutan war of 1865, they then added this newly annexed area to the existing Darjeeling region and formed a formal district.
Given the fact that this new area was unlike any other, the British designated the area as a "non-regulation area", which meant that any act or regulation passed in the rest of India, would not come into force in the Darjeeling region, unless they were specially extended to it. In 1919, the Government of India Act formed the Legislative Council. Darjeeling was not required to send any member to it. The district was excluded and declared a backward tract and the administration was under the Governor in Council.
The only connection, Darjeeling region had to Bengal in those days was that the Governor of Bengal presidency also acted as the Governor for the Darjeeling region. It is evident from the fact that any Act passed by Bengal government, which automatically extended to whole of Bengal, would not apply to Darjeeling indicating that the Darjeeling region was never a part of Bengal.
Exactly 100 years after taking control of the Darjeeling region, the British Government passed an Act in 1935 requiring the three hill subdivisions to send a representative to Bengal's Legislative Assembly for administrative ease and Dambarsingh Gurung (a Gorkhali) became Darjeeling's first MLA to Bengal and that is how Darjeeling was now pushed into Bengal; merely for administrative ease by the British.
The people of Darjeeling, Doars and Terai region are predominantly ethnic Gorkhalis, who do not share any linguistic, cultural or traditional affinity to the rest of Bengal. This has resulted in a large-scale deprivation of ethnic local communities such as the Gorkhalis, the Kamtapuris and the Rajbanshis.
The inflow of refugees from Bangladesh, which started as a trickle in 1965 had grown into a rushing torrent by 1971 and every Government of West Bengal since then has allowed these refugees and later illegal immigrants to settle in the areas bordering the Darjeeling, Terai and Doors.
The CPI(M) after coming to power in 1979 institutionalized this practice and consolidated these illegal immigrants as their vote bank, which in turn allowed them to rule over Bengal for over 34 years. The influx of these illegal immigrants has in turn lead to the marginalization of the ethnic Gokrhali, Kamtapuri and the Rajbanshis.
Much like the rest of the North Eastern India the illegal Bangladeshi immigrants far outweigh the local ethnic population, which has cause widespread discontent and sense of neglect amongst the ethnic population of the region. Hence, the demand for a separate state of Gorkhaland which will ensure that the critical chicken-neck area of India is protected from these state sponsored illegal immigrants from Bangladesh.
Please note that most of the information used here are based on articles written by Dr. Sonam B Wangyal (an eminent historian of the region) in darjeelingtimes.com over the years which were collected by the author and used to develop this article.