Cangzhou is not a geographical Cangzhou, but a place beside the water, which means seclusion.
Seclusion, probably after old age, disheartened, or resentment and silence about the status quo.
Therefore, Cangzhou is often associated with the elderly.
Many place names in poetry are best not to be specific to the real geographical location.
Lu Fangweng's "Confessions": In this life, who knows, my heart is in Tianshan Mountain and my body is old in Cangzhou.
Tianshan and Cangzhou are empty, Tianshan refers to frontier fortress, and Cangzhou refers to seclusion. According to the actual location, Cangzhou is in Xu Jinguo, and Lu Fangweng can't go if he wants to.
Zhou comes from Sichuan, which means land in water.