After Allya's passing, there was a short struggle for power between the eldest daughters. Before the conflict turned violent, it was decided that it was time for the immense family to break away from one another. Each of the original daughters left the group, taking their extended families with them.
The generations that have passed since the time of Allya have had their toll on the anicent teachings of the Force. The way of the Jedi has been replaced by a more primitive school. The Force-users of Dathomir (who refer to themselves as "Witches") use a variety of chanting, singing, dancing, and written words to access the Force. Allya has become more of a figurehead to be worshipped than an infinitely removed grandmother.
Each clan began to grow, the sisters studying the "magic" of Allya and the manslaves hunting for food, tending to the children and obeying the Witches. Throughout this time each clan developed their own versions of Allya's magic, known now as "Allyan Magic". The effects of these powers, though the means by which each spell is cast differs from one clan to another.
This also changed the Book of Law a great deal. Each clan holds a version of the Book. Though they all contain the orginal teachings of Allya, each Book has been added to over time by each clan. They all speak of similar lessons, but with different methods of attaining goals.
Generations passed and each clan continued to grow in numbers and in power. Though territorial arguments sometimes broke out, the clans usually managed to keep their control and work things out without violence. It was not until an immense ship, called Chu'unthor, crash-landed on Dathomir that violence was introduced to the Witch clans.
Female, male and alien Witches came out of the Chu'unthor's ashes. The sudden wave of pure energy that overtook the planet greatly disturbed the simple Witches of the planet. In reaction, the Witch clans united and attacked the newcomers. When news of this reaction reached Old Republic space, a group of Jedi were assigned to rescue the surviving acolytes. Eventually, the two sides gave up their battle, once again returning to their peaceful ways.
Dathomir Clans (There are nine clans of witches on the planet, although there are 4 listed):
Frenzied River Clan
Misty Falls Clan
Red Hills Clan
Singing Mountain Clan