Complex sentence: They had numbered over 1 million in 1980, or 7% of the population, but almost 400,000 fled to other countries, especially after the Invasion of Iraq in 2003.
Split into simpler sentences: They had numbered over 1 million in 1980, or 7% of the population. Almost 400,000 have fled to other countries, especially after the Invasion of Iraq in 2003.