Due to increasing efforts of standardization in the 19th and 20th centuries, the localized forms present in different districts and also among the remaining source-cultures with the less-assimilated ethnocultural groups have seen greater alienation. However, Assamese culture in its hybrid form and nature is one of the richest and is still under development. 20th century saw numerous self-determination and identity movement and many states were new states were created in the process as most indigenous tribal communities of the state refused to accept the idea of collective Assamese identity which was imposed upon them. Many indigenous tribal communities of the state still oppose the efforts of assimilation into Assamese cultural identity.