 Sun's mother had taken her to Wuhan after Sun's father was executed by the KMT in 1927, during the White Terror.Zhou came upon the sixteen-year-old Sun crying outside of the Eighth Route Army Liaison Office because she had been refused permission to travel to Yan'an, due to her youth and lack of political connections.After Zhou befriended and adopted her as his daughter, Sun was able to travel to Yan'an.