What might this fantasy culture look like?

[MonkeySage]

I'm working on a writing up a matriarchal society ruled by a caste of mages in the extreme north.

This rigid caste system would look like:
Witch- Always female, follow a strict code of conduct. Serve as spiritual leaders, delegates, healers, and mediators between the living world and the spirit world. They live in a community owned house, and hold no official political power. They are kept well fed, but expected to keep a modest lifestyle.

Each Witch represents a realm.

Warrior- Charged with the task of hunting game and protecting the land and its people. Occasionally, a member of this caste is assigned to the defense of their Witch. Warriors are sometimes male, but are predominantly female.

Commoners- Self explanatory, though sometimes a female commoner is selected to become the apprentice of a Witch. The appointment is mandatory, and the appointee is typically under the age of 10.

[VoxRationis]

You said the witches hold no official political power. Who does?

Also, the system you've got can't generally be called a "caste" system according to common definitions of the word, since witches take on apprentices from commoners and clearly the children of one group aren't inherently going to go into that group (since any male children witches bear are going to go down one or two steps).

[MonkeySage]

Fair enough... hmm, well, not in the traditional sense I suppose. A class system sounds more appropriate. Nonetheless, there isn't much in the way of upward mobility; commoners cannot become legitimate warriors, warriors are not eligible to become witches, etc.

They don't really have a political authority in the commonly understood sense. The Warriors and Commoners convene in a sort of village council, and the Witches serve as delegates. I suppose it isn't entirely accurate to say they are the rulers. Each of the classes plays a sort of rulership role in its own right; witches are advisers and delegates, warriors are the protectors and hunters(hunting being extremely important as a source of both clothing and food), commoners being fishermen, craftsmen, etc(there aren't really very many farmers, climate doesn't lend itself well to agriculture). Warriors and Commoners both vote in village councils, while Witches bring wisdom to the table.

[shawnhcorey]

You should read up on bonobo social structure since their society is dominated by females.

[Xuc Xac]

What are the witches "delegates" of or to? A delegate is like a representative or an ambassador. Who do they represent and where do they go to represent them?

[MonkeySage]

The three realms they represent make up a small territory in the far north. Immediately surrounding them are five warrior kingdoms who are barely kept from invading by delicate diplomacy. The Witches serve as delegates to these five kingdoms, but also as delegates between the villages in each of those three realms, and amongst the three realms. The three witches normally meet up on a biweekly basis at a house that sits between all three realms.