Complex sentence: Gradually, his fellow gunmen scattered to their various fates, and he rode with Bowdre, O'Folliard, Dave Rudabaugh, and a few other friends, with whom he rustled cattle and committed other crimes.
Split into simpler sentences: Gradually, his fellow gunmen scattered to their various fates. Billy rode with Bowdre, O'Folliard, Dave Rudabaugh, and a few other friends, with whom he rustled cattle and committed other crimes.