One such method is that of ethnography: basically, they advocated living with people of another culture for an extended period of time, so that they could learn the local language and be enculturated, at least partially, into that culture.
Immik iyyan chund wen eqqal wan teɣare n agna: asilmadan hullan s tamazzuq id addinat n agna iyyan har azzaman hin inkachan ; har ilmidan agna n akal d war he assujalan kuddeɣ s achrut daɣ agna iyyan