Complex sentence: In 1962, when an invitation was extended by Stanford University to substitute for a professor on special assignment, he readily accepted and returned to the U.S. after having lived full-time in Japan from 1948 to 1962.
Split into simpler sentences: In 1962, when an invitation was extended by Stanford University to substitute for a professor on special assignment, he readily accepted. He had lived full-time in Japan from 1948 to 1962.