Complex sentence: The port town of Boma (1984 pop.197,617) was the capital city of the Belgian Congo (the modern Democratic Republic of the Congo) from 1 May 1886 to 1926, when it was moved to Léopoldville (since renamed Kinshasa).
Split into simpler sentences: The port town of Boma (1984 pop.197,617) was once the capital city of the Belgian Congo (the modern Democratic Republic of the Congo). In 1926, the capital was moved to Léopoldville (since renamed Kinshasa).