Knew Not Joseph

Exodus 1:6-8 states: 
⁶ Then Joseph died, and all his brothers, and that whole generation. ⁷ But the Israelites were fruitful and prolific; they multiplied and grew exceedingly strong, so that the land was filled with them. ⁸ Now a new king arose over Egypt, who did not know Joseph. ⁹ He said to his people, “Look, the Israelite people are more numerous and more powerful than we. ¹⁰ Come, let us deal shrewdly with them, or they will increase and, in the event of war, join our enemies and fight against us and escape from the land.”
Exodus 1:6-8  (NRSV). 

The phrase "did not know Joseph"   is full of meaning, as described by Sarna: 

This is the first appearance in Exodus of the verb y-d-ʿ [know]. It is a key term in the Exodus narratives, occurring over twenty times in the first fourteen chapters. The usual rendering, “to know,” hardly does justice to the richness of its semantic range. In the biblical conception, knowledge is not essentially or even primarily rooted in the intellect and mental activity. Rather, it is more experiential and is embedded in the emotions, so that it may encompass such qualities as contact, intimacy, concern, relatedness, and mutuality.  Conversely, not to know is synonymous with dissociation, indifference, alienation, and estrangement; it culminates in callous disregard for another’s humanity.  
Nahum Sarna,   The JPS Torah Commentary: Exodus שמות (Jewish Publication Society, 1991).