Complex sentence: In 1918 when the Whites controlled the Northern Territory with a population of about 400,000 people, more than 38,000 were sent to prisons, of which about 8,000 were executed while thousands more died from torture and disease.
Split into simpler sentences: In 1918 when the Whites controlled the Northern Territory with a population of about 400,000 people, more than 38,000 were sent to prisons. Of those, about 8,000 were executed while thousands more died from torture and disease.