[1] Assam has been settled by colonial officials (amlahs) from Bengal pre-Independence and Hindu Bengali refugees in the post-Independence periods.
The term lent the name to the Bongal Kheda movement of the 1950s and 1960s which sought to drive out non-Assamese competitors and to secure jobs for the natives.
The Assamese people viewed Bongal was someone who didn't belong Assam, an intruder whose presence threatened to marginalize them socially and politically.
An 1872 Assamese play by Rudra Ram Bordoloi titled 'Bongal Bongalini' lampooned the social problems created by the outsiders i.e. the Bongals, especially who came during the British rule.
This grew resentment in the Assamese community and after many Instances of Bengali-assamese feuds this resentment soon led to the movement called 'Bongal Kheda', literally meaning 'drive away the outsiders(here referring to the Bengali populus)', which resulted in many protest, vandalisation of property and attack on the Bengali Hindus state-wide.
In the seventies it spread to other tribal northeastern parts of assam with significant Bengali population with similar condition likes Meghalaya and Tripura mostly under Assamese influence.