Men did not dominate women. There was a sexual division of labour, with men tending to do the hunting while women gathered, but this did not mean female domination. What little private property that existed was passed down the female line. The reason for this was that women could take several partners, thus making it impossible to know who the father was with any certainty. The next stage is that of Barbarism.
Men begin to domesticate cattle.
They are unwilling to let it pass down the female line and so start to impose restrictions on women's sexual activities. Eventually monogamy comes to be the most predominant form of marriage. As women are pushed into the family and excluded from owning private property so they become dependent on men and are thereby dominated. Because women do not own private property they have little power in relation to men. Engels was unfortunately writing at a time when details about the past where quite sketchy.