Complex sentence: This Age was the first relatively stable Age Gehn wrote as he was trapped on Riven with no way out, his previous attempts had all failed either because of his flawed Writing, or the lack of a power source for his Books.
Split into simpler sentences: This Age was the first relatively stable Age Gehn wrote as he was trapped on Riven with no way out. His previous attempts had all failed either because of his flawed Writing, or the lack of a power source for his Books.