In order for the intrusive language to persist (substratum case), the immigrant population will either need to take the position of a political elite or immigrate in significant numbers relative to the local population (i. e., the intrusion qualifies as an invasion or colonisation; an example would be the Roman Empire giving rise to Romance languages outside Italy, displacing Gaulish and many other Indo-European languages). The superstratum case refers to elite invading populations that eventually adopt the language of the native lower classes. An example would be the Burgundians and Franks in France, who eventually abandoned their Germanic dialects in favor of other Indo-European languages of the Romance branch, profoundly influencing the local speech in the process.