Some scholars also believed that assimilation and acculturation were synonymous. Omitting indigenous knowledge amounts to cultural assimilation. Some nation-states pursued violent policies of cultural assimilation and even ethnic cleansing. Focus has shifted from a rhetoric of cultural assimilation to cultural integration. Muslim rule differed from these others in the level of assimilation and syncretism that occurred. Migration and military expeditions led to the cultural assimilation of the south. A major issue concerned assimilation and syncretism. These politicians often focus on the debate over cultural assimilation and integration. Such people vary widely in terms of cultural assimilation. Several physiological processes may be responsible for linking photorespiration and nitrogen assimilation. Ultimately almost all biomolecules come from the assimilation of carbon dioxide in plants during photosynthesis. Studies have also noted the positive effects of immigrant assimilation. Creolization, assimilation and integration have been continuing processes. Initially, the Khmer Rouge aimed for the "forced assimilation" of Chams through population dispersal. They gave Scots a path to assimilation and cultural integration as Scottish New Zealanders.