Passage: Later on, the States of Cao and Song became hostile towards each other. Duke Jing of Song captured Duke Dao of Cao in 515 BC and held him prisoner until his death. Thereafter, disorder broke out in Cao and Duke Dao's successors Duke Sheng of Cao and Duke Yin of Cao were killed one after another. Duke Fei of Cao became ruler and betrayed the State of Jin by invading the State of Song. As a result, Duke Jing of Song attacked Cao. No troops from the State of Jin came to the rescue such that the State of Cao was exterminated in 487 BC after the capture of Duke Fei of Cao.

Question: Which states became hostile to one another?
States of Cao and Song