What does Isaiah 19:11 mean?

Ancient Egypt was famous for more than abundant crops, fishing industry, and linen (Isaiah 19:5–9). The nation was also renowned for its learned men and wisdom literature (1 Kings 4:30). In part, this involved cultural appreciation of the wisdom handed down from one generation to the next. Decisions were recorded and preserved to be consulted by future groups of counselors.

Isaiah's oracle from the Lord (Isaiah 19:1) shows how worthless Egyptian wisdom is compared to God's judgment. The city of Zoan, or Tanis, was the chief city situated on the eastern side of the Nile delta. It was also sometimes the capital of northern Egypt. The officials of Zoan were the important men in Egypt during this era. Egypt's king, the Pharaoh, turned to them for counsel and advice in leading the nation.

The prophet calls these men completely foolish and their advice stupid. He asks them in his poem how they can possibly call themselves the "sons of the wise" or "the sons of ancient kings." Isaiah uses the rhetorical question to declare that these men can't possibly live up to the reputation of Egypt's wise men of old.