Her father was Emperor Magnus Arias and the mother - Kaira Faran. When Magnus banished his wife from the palace because he fell in love with Dryad, Alyah never forgave him for that and so, she left the palace and becomes a rogue.
Later, Magnus was killed by Alyah herself. Empyria loses the ruler and Alyah must have become a hier of the throne.
In SpellForce 2: Demons of the Past, when you meet Alyah in the Realm of the Gods, she tells you, that she had died during the war against the Hazim.