Complex sentence: After the Vietnam War ended in 1975, the victorious Vietcong forces reunified the northern and southern halves of the country, many people began to migrate out of fear of the new Communist Government.
Split into simpler sentences: After the Vietnam War ended in 1975, the victorious Vietcong forces reunified the northern and southern halves of the country. At this time, many people began to migrate out of Vietnam out of fears of the new Communist Government.