Gorkha people living in the proposed Gorkhaland state now consists three types of people: (1) decedents of Nepali/Gorkha people living in the region long before creation of India (2) some of the ex serviceman of Gorkha regiment who decided to settle in Darjeeling Hills (3) people and their decedents who moved from Nepal to the Darjeeliing area after Indo-Nepal treaty of 1950 searching for job.
"Shah Dynasty" was established in the "Gorkha Kingdom" by Drabya Shah (1559-1570) replacing competitive ghale Kings. His 10th generation, King Prithvi Narayan Shah, the great (1723-1775), started unification of pan himalayan region in 1744 under one flag and carried it until his death in 1775. His successors continued the unification process until 1791 expanding from small 5,000 sq km principality to large 250,000 sq km nation. In 1779 during the unification, capital of newly untied Gorkha Kingdom was moved from central Gorkha to Kathmandu Valley aka Nepal. From that point Kingdom of Gorkha called Kingdom of Nepal and the Khaskura or Gorkhali language (language of the original gorkha principality) called Nepali language. At its height in 1791, Kingdom of Gorkha/Nepal consisted landmass from Teesta River in the east bordering Bhutan (consisting all area present day Sikkim state and proposed Gorkhaland state of India) and Satlaj River in the west bordering Punjab Kingdom.
After anglo Nepal war (1814-1816) and Sugauli Treaty(1816) Nepal lost Sikkim Kingdom which also consisted Darjeeling at that time in the eastern side. But many ethnic Nepali/Gorkhali people remained there under Sikkim and British Raj.
Sugauli treaty(1816) also facilitated the creation of a Gorkha Regiment in British Indian force recruiting from Nepal. After the independence of India in 1947 Gorkha regiment was partitioned into British Gurkha and Indian Gorkha. And for both of the regiments people are still being recruited exclusively from Nepal. Nepali citizen now serve in Indian Army Gorkha regiment without being citizen of India. Majority of Ex.Serviceman of Indian Gorkha regiment come back to homeland Nepal after their service but some choose to settle in India, predominately in Darjeeling, as this area is already populated by Nepali language speaking similar people.
Also, as the 1950 Indo-Nepal treaty allowed citizens of Nepal and India to live in each others country legally, many Nepali people have been moving to Darjeeling hills looking job opportunity in Tea plantations and settled there (likewise many Bihari people have been moving to terai region of Nepal searching for job opportunities).
Timeline of Gorkhaland
1789: Kingdom of Gorkha/Nepal conquered Sikkim Kingdom which also covered proposed Gorkhaland at that time.
1816: After Anglo-Nepal war Sugauli Treaty was signed and Nepal gave up Sikkim.
1850: British EIC annexed 1700 sq kms of current Darjeeling district from Sikkim. Following 1864 Treaty of Sinchula with Bhutan and Darjeeling district got its current shape in 1866 covering 3200 sq km area.
1864: Darjeeling became the summer capital of Bengal Presidency (British indian sub division).
1936 June 22: Subhash Ghising was born in Darjeeling, British India.
1964 July 17: Bimal Gurung was born.
1947: After independence of India, darjeeling was merged in State of West Bengal.
1975: Kingdom of Sikkim was annexed by India.
Communist Rule in West Bengal
1977: CPI Marxist won majority 178 seats among total 294 seats in West Bengal legislative assembly defeating ruling Congress I. Jyoti Basu became the chief minister of West Bengal. CPI-M rule was ended only after 34 years by 2011 election.
1980: Subhash Ghising established "Gorkha National Liberation Front - GNLF", a political party demanding separate Gorkhaland State in India.
1st Gorkhaland people's movement
1986-1988: people's movement led by GNLF erupted in the Darjeeling hills demanding separate State on the basis of ethno-linguistic rights. About 1,200 people lost their lives.
1988 Aug 22: Darjeeling Hill Accord was signed. "Darjeeling Gorkha Hill Council - DGHC", a semi-autonomous body for the administration of Darjeeling district, was established. GNLF gave up its demand for separate Gorkhaland State.
1992: Government of India recognized Nepali language (which is also the main language of Sikkim) including it in the 8th Schedule of the Constitution of India.
2nd Gorkhaland People's movement
2007 Oct 7: Bimal Gurung established Gorkha Janmukti Morcha (गोर्खा जनमुक्ति मोर्चा).
2009 Apr/May: 15th Lok Sabha election. National level leader Jaswant Singh from BJP won the Darjeeling constituency with 51.5% popular vote. But as INC alliance got majority seat in Lok Sabha BJP leader found an excuse not to fulfill his promise to help grant Gorkhaland statehood.
Rule of Mamata Banerjee in West Bengal State
2011 May 20: All India Trinamool Congress pulled off a landslide victory defeating 34 years long Communist rule in west bengal state. Mamata Banerjee appointed as the Chief Minister.
2011 July 18: "Memorandum of Agreement" for "Gorkhaland Territorial Administration- GTA" was signed near Siliguri in the presence of Home Minister of India P. Chidambaram, West Bengal chief minister Mamata Banerjee and Gorkha Janmukti Morcha leaders. GTA replaced 23 years old "Darjeeling Gorkha Hill Council - DGHC". The new GTA will have 50 members: 45 of them will be elected and the rest nominated. (Link) (Link)
2013 July 30: Mangal Singh Rajput (45) set himself in fire demanding Gorkhaland State (he died Aug 3 in Siliguri in Hospital) (Link)
2014 Apr/May: 16th Lok Sabha election held. S. S. Ahluwalia from BJP won the Darjeeling constituency(wiki) with 42.75% popular vote getting support from Gorkha Jamamukti Morcha-GJM. Ex football player Bhai Chung Bhutia, contested from West Bengal's ruling All India Trinamool Congress, got second in the competition with 25.48% popular vote.
2016 Apr/May: West Bengal Sate's 294-seat Legislative Assembly election held. All three candidates from GJM in Gorkhaland GTA area (Sarita Rai, Amar Singh Rai, Rohit Sharma) won the election.
2017 May-June: West bengal government decided to include mandatory Bengali language curriculum in School. Protesting the governments decision new agitation erupted in Darjeeling supporting Gorkhaland. Three people killed by Army in the agitation.
Timeline of Sikkim in India (1975 - present)