More Historical Assimilation
Historically, cultural assimilation took centuries to completely assimilate a culture. Much of the demographic changes were due to migration instead of assimilation. For example, in the early 1900s, there were still over a million Greeks in Anatolia.
This mod changes some values to make cultural assimilation much slower. The Assimilate Pops cabinet action is reduced by 75%, and the dominant culture modifier only adds 10% assimilation instead of 50%. It also allows non accepted cultures to grow in integrated areas. There are also other smaller changes that lower assimilation.