What does Joshua 10:1 mean?

When Adoni-Zedek, king of Jerusalem, heard that Joshua had taken Ai and destroyed it, and that he had done the same to Ai and its king as he did to Jericho and its king, and that the people of Gibeon had made peace with Israel and were living among them, he got really worried. Joshua 10:1 - Modern Text Bible

(The king of Jerusalem is alarmed by Israel's victories and Gibeon's alliance with them.)