A past society would be an other culture separated by what temporal aspect?
For example, the classic of urban anthropology, Ulf Hannerz in the introduction to his seminal Exploring the City: Inquiries Toward an Urban Anthropology mentions that the "Third World" had habitually received most of attention; anthropologists who traditionally specialized in "other cultures" looked for them far away and started to look "across the tracks" only in late 1960s.