Consider the Burgundians. Not a distant, bizarre Amazonian culture from Bolivia, but a Scandinavian/Germanic/Frankish one not altogether dissimilar to the Anglo-Saxons who are our direct cultural ancestors. Their legal code contains the following provision:
XII OF THE STEALING OF GIRLS.
1. If anyone shall steal a girl, let him be compelled to pay the price set for such a girl ninefold, and let him pay a fine to the amount of twelve solidi.
2. If a girl who has been seized returns uncorrupted to her parents, let the abductor compound six times the wergeld of the girl; moreover, let the fine be set at twelve solidi.
3. But if the abductor does not have the means to make the abovementioned payment, let him be given over to the parents of the girl that they may have the power of doing to him whatever they choose.
4. If indeed, the girl seeks the man of her own will and comes to his house, and he has intercourse with her, let him pay her marriage price threefold; if moreover, she returns uncorrupted to her home, let her return with all blame removed from him.
5. If indeed a Roman girl, without the consent or knowledge of her parents, unites in marriage with a Burgundian, let her know she will have none of the property of her parents.
Imagine what it would be like to live in such a society (although I think giving over the abductor of a girl to her parents granting them "they power of doing to him whatever they choose" is the kind of law a large section of the readership of The Daily Mail could get behind). Obvious gender politics aside, I find the economics of it fascinating: this was a society in which, if you had money, you could quite literally do whatever you wanted. See also the fines for murder:
- A murdered slave, 30 solidi
- A murdered carpenter, 40 solidi
- A murdered blacksmith, 50 solidi
- A murdered silversmith, 100 solidi
- A murdered goldsmith, 200 solidi
So not only could you simply give financial recompense for murder (something we cannot imagine in our society today), the amount owed depended on who you murdered. In modern societies the notion that one person's life is worth more than another's is simply not tolerated.
There are other unusual provisions - for instance, the code also fixes a price of 12 solidi for "A woman whose hair is cut off without cause"; this is apparently because, in Burgundian society, a woman's hair could be cut off to allow her to become a warrior. Meanwhile, refusing hospitality to anybody (literally anybody at all) was punishable by a fine of 3 solidi "for the neglect".
In all respects this was an alien legal system and an alien culture - but it is one from which our modern law and culture is largely descended. So what kind of cultures would exist in a fantasy world bearing no relation to our own? Note: I'm not suggesting that exploring issues of patriarchy and historical materialism would be interesting in a game - just that people in the past in our own world were really weird by our own standards, so fantasy humans on a fantasy world should surely be weirder still.