Complex sentence: In 1947, Medan became capital of East Sumatra with Tengku Mansur as State Mayor, after the RIS era ended, Medan officially became the capital of North Sumatra.
Split into simpler sentences: In 1947, Medan became the capital of East Sumatra with Tengku Mansur as State Mayor. After the RIS era ended, Medan officially became the capital of North Sumatra.