Uttarakhand is a hill state mainly consisting of two ethnic groups (Garhwali and Kumouni) from two ancient Hindu Kingdoms-Garhwal Kingdom and Kumaun Kingdom.
Culture and language of both of these groups were very different from main land Uttar Pradesh.
When Uttarakhand was part of Uttar Pradesh, this particular region was ignored because it had no political importance in UP. The reason was the low density population of Kumauni and Garhwali people was very less, where only 2 seats in Indian Parliament and around 15 seats in Uttar Pradesh Assembly were given to Uttarakhand. During 1990’s caste based politics was on rise where SP and BSP were in charge of UP, and hill region (which had mainly Rajput and Brahmin) didn’t provide any political benefit to these parties. Both of these parties intensified separatism by giving “Anti Uttarakhand” statements in media.
Then Uttar Pradesh CM, Mulayam Singh Yadav allegedly charged violence against Uttarakhand activists. At Rampur Tiraha, Uttar Pradesh police fired openly on activists, many cases were reported at the same venue. Long term ignorance of the region lead to the unemployment and poverty in the Hill region, which insisted demand for separate statehood and further violence involved in Rampur Tiraha proliferated the fire of Uttarakhand Revolution for separate statehood within India. After that just before General Elections, BJP leader and then CM of Uttar Pradesh Kalyan Singh promised the formation of Uttarakhand state within 90 days if BJP gets elected to the centre. People of Uttarakhand flooded all the votes for BJP and Atal Bihari Vajpayee in General Election 1999. BJP formed the government at centre and Vajpayee got elected as Prime Minister.
Under PM Atal Bihari Vajpayee, centralgovernment on 27th July 2000 presented the bill for separate state of Uttarakhand and on 9 November 2000 the new state Uttaranchal came into existence as the 27th state of India which is now known as Uttarakhand.