Complex sentence: In the early 1900s, Sonsón was the second city in Antioquia after Medellín, the capital, it had many factories, and most of the rich people in Antioquia had business there.
Split into simpler sentences: In the early 1900s, Sonsón was the second largest city in Antioquia after Medellín, the capital. Sonsón had many factories, and most of the rich people in Antioquia had business there.