It began when the Dark Ireland, namely the Morganna; Morrigan, Macha, and Scald Crow, laid seige to the Forest of Nil. Trees began to burn and nature cried out in agony. Dierdriu and her army, the Fianna, were alerted and surged forth into the trees, dousing fires and fighting the blackness. After many days of fierce battle no force was even close to victory. Dierdriu had no choice, she cast an enchantment and put the trees to sleep, so none could posess them. This infurated Morrigan so she cursed Dierdiru and the House of Tara.
"Shall a human ever sit upon Tara's throne again the Dark Ireland will surge forth and destroy Ireland. The skies will grow black and the rivers shall run with blood"
So Tara's curse was created. Now all you know that a curse cannot be destroyed, only bypassed, and that is exactly what Dierdri did, she bypassed the curse. She approached the sorcerors and asked them to create an enchantment that would allow the nobilty to lay with the beasts of Ireland, to create half breed offspring, so a human would not sit on the throne. They did and the six noble house of Tara were born, The Wolves, The Lions, The Panthers, The Eagles, The Swans, and the Chariot Horses. Minor Bllodlines were created after, awarded to those who served the king well, creating many more diffrent familes of the bloodline.