Complex sentence: In 1976, Reverend Okumura came to the United States to help build Pioneer Valley Zendo in Massachusetts where he practiced until 1981 when he returned to his homeland of Japan.
Split into simpler sentences: In 1976, Okumura came to the United States to help build Pioneer Valley Zendo in Massachusetts. Okumura stayed here until 1981 when he returned to his homeland of Japan.