Ignorant Mainlander's questions about Assam(CONTROVERSIAL and SORRY)?

Hi,this is a throwaway account.I am an ignorant Mainlander(or Bongal/Dkhar/Mayang/Haring/Vai/Oppressor/Colonist/Indian or whatever) from South India.I am currently reading about the insurgencies in the North-East(read through Sanjib Baruah's last volume,Longkumer and Sethji and Shubharastra) and asked people from this region online. I always wondered one thing,why do the Assamese have such strong separatist sentiments(i have noticed that many Assamese people are far more racist against Mainlanders compared to groups like Nagas).I can see why groups like Zos,Nagas,Khasis and Meiteis have such sentiments(honestly,i think these regions would have been better off being under Bhutan,Burma or a independent protectorate(like Bhutan)) due to ethnic differences and government mismanagement but why Assam? Assam has stronger cultural ties to the Mainland(which is a diverse region home to many cultures,religions,races and ethnicities).Not only was Assam influenced by the Mainland,Assam also influenced Mainland culture as well since Assam was a major center of Tantra in Hinduism and Buddhism and produced many notable scholars of Hinduism and Buddhism like Matsyendranatha,Kumarila Bhatta,Luipa and texts like Kalika Purana and Hevajra Tantra. Assam also seems far more similar to regions like Odisha(i would have gone with Bengal but Assamese and Bengali societies are radically different culturally and considering the tensions,i would be going with Odisha).Both,Assam and Odisha are home to a lot of tribal groups of mixed Indian and SE Asian origins(like Austro-Asiatic Mundas and Dravidian Tribes in Odisha and Bodo-Kachari groups in Assam) alongside Indo-Aryan groups and both regions are Vaishnavitie Eastern Indo-Aryan speaking regions who maintained cultural and political independence from Northern India(like Ekasarana Naam Dharma,Sattriya and Borgeet Music in Assam and Odissi dance,Music and Utkaliya Vaishnavitism in Odisha).Additionally,both regions suffered from insurgencies and neglect and atrocities from the center.Yet,i rarely see separatist sentiments and racism from Odias but not from Assamese?