Complex sentence: In 1933, the Japanese attacked the Great Wall region, the Tanggu Truce taking place in its aftermath, giving Japan control of Jehol province as well as a demilitarized zone between the Great Wall and Beiping-Tianjin region.
Split into simpler sentences: In 1933, the Japanese attacked the Great Wall region. The Tanggu Truce established in its aftermath, gave Japan control of Jehol province as well as a demilitarized zone between the Great Wall and Beiping-Tianjin region.