What culture is it where they are separate from men and live mainly all women?

The culture you're referring to may be the Mosuo people in China, often described as a matrilineal society. In this community, women hold primary authority, and family lineage is traced through the female line. While men are present in the community, they typically do not live in the same households as women, leading to a unique social structure. The Mosuo are known for their practice of "walking marriages," where women choose partners without the expectation of traditional marriage.