Assimilation history is irrelevant when it comes to today's world.

Immigrants from very different cultures find it easy to live here without assimilation... and to retain regular contact with their homeland. That was a lot harder in the age of mass migration from Europe AND earlier immigrants were primarily from Western countries. Today, Asians and Southeast Asians are enthusiastic about adapting. We should continue to facilitate the immigration of talented people from these cultures because they fit in and become valuable citizens quickly. This is less true with folks from cultures who continue to have more primitive and superstitious world views. We need to screen them more assiduously and limit their numbers.