Most societies seem to be more patriarchal, but surely there have been some with women as the leaders / more dominant members of society? Or even simply gender equality (even knowing that equality is somewhat subjective).
First and foremost we'd have to define this matriarchy thing because leaders and dominant members of the society can be female even if the society is pronouncedly not.
For the Marxists, through Frederick Engels and Lewis H. Morgan, and consequently for Second Wave feminists matriarchy was a society where women were the ones who owned and bequeathed wealth, where it was the woman who was the head of the family unit. Lewis H. Morgan was an American lawyer who defended the property rights of the Iroquois Indians and he noticed what? They didn't have a concept of fatherhood. They lived in large long-houses which were owned by the oldest female, by the matriarch. The males were usually busy hunting and going to war and romance was done by getting adopted by one of these female families for that joyous while.
The male was not related to the kids he fathered in any way. You didn't quite know which kid was done by whom. So they remained bound to their mothers alone. They also had none of the strict fidelity laws that we know from Agrarian Societies, from the Ancient Jews, from the Mesopotamians, the Greeks, the Chinese, the Aztecs, to whom the women were the house slaves forced to be "loyal" with draconic laws so that the dudes could say which of the little kids they sired, so they could tell their heir apart.
There are still matriarchist societies like the one described by Morgan in America. The Meghalaya in India for example were mercenaries. They did have fatherhood but women owned everything while their men were busy getting killed in wars. If a woman doesn't like a man she has the right to banish him and take another husband in his place. The men there are slaves just like the women are in the tribal areas of Pakistan and in Afghanistan
There are also matriarchist societies in Vietnam. It is worth saying that just as a patriarchist society can be ruled by a female (think Benazir Bhutto), matriarchist ones can be ruled by men. The first and prime example, the Iroquis, were for example ruled by a male chieftain because the chieftains had to know a thing or two about going to war.
Source: The Second Sex by Simone de Beavoir, the History of the Family by Frederick Engels, Ancient Society by Lewis H. Morgan.
The most extreme example are of course the Dahomey, subjugated by France in the late 19th century. They were female warriors living from slave trade.
