Complex sentence: During the 19th and 20th Dynasties, the Meshwesh were in almost constant conflict with the Egyptian state, ultimately taking control of the country during the late 21st Dynasty under king Osorkon the Elder.
Split into simpler sentences: During the 19th and 20th Dynasties, the Meshwesh were in almost constant conflict with the Egyptian state. They would ultimately take control of the country during the late 21st Dynasty first under king Osorkon the Elder.