What information specifically convinced the people that these new dragons weren't here to harm them?

Despite confirmation from both the Lord of Palanthas and the head historian, Astinus' confirmation that the dragons that had just arrived fought on the side of what was good and right, it wasn't this information that led the people to believe that the dragons weren't going to hurt them. It wasn't until Laurana embraced one of the riders; her brother, that the people began to lower their weapons.