Complex sentence: Nataku served 500 years long before the beginning of "Gensomaden Saiyuki" because of his taboo blood he was ordered to subdue the Bull demon Gyumaoh and his minions with the help of the heaven army.
Split into simpler sentences: Nataku served 500 years long before the beginning of "Gensomaden Saiyuki". Because of his taboo blood, he was ordered to subdue the Bull demon Gyumaoh and his minions with the help of the heaven army.