Complex sentence: After escaping, Tintin discovers a source of underground petroleum, following which the U.S. army forces the Natives off their land, and oil companies build a city on the site within 24 hours.
Split into simpler sentences: After escaping, Tintin discovers a source of underground petroleum. The U.S. army then forces the Natives off their land, and oil companies build a city on the site within 24 hours.