>In the five centuries between Caesar's conquest and the collapse of the Western Roman Empire, the Gaulish language and cultural identity underwent a syncretism with the Roman culture of the new governing class, and evolved into a hybrid Gallo-Roman culture that eventually permeated all levels of society
https://en.m.wikipedia.org/wiki/Roman_Gaul
Can you point to symbiosis with native American culture that resembles that to any extent today in the US? All we have are racist football team mascots