Xiao Yao Wan for Migraine

I have suffered from migraines and recently read of an herb called Xiao Yao Wan that helped with migraines. Can you tell me what it is and a little bit about it?

Xiao Yao Wan (also known as Hsiao Yao Wan) is a Chinese patent medicine used mainly to relieve liver "stagnation". It is made of a combination of herbs including bupleurem, dong quai, bai zhu, Chinese licorice, and others.
In the Chinese medical system seemingly unrelated organs can be related through the "chi" or energy system in the body. So, although this combination's main effect to is promote liver function, it is also known to relieve a wide variety of symptoms, including headache associating with a weak liver and "deficient blood". Just you give you some idea of the range of indications this medicine is used for, here are some: irregular menstruation, hepatitis, pleurisy, cystic hyperplasia of the breast.