Adam Clarke on Joshua 10:2

As one of the royal cities - Not a regal city, but great, well inhabited and well fortified, as those cities which served for the royal residence generally were. It does not appear that the Gibeonites had any king - they seem to have been a small but powerful republic, all the men thereof were mighty, merely governed by their elders: for in their address to Joshua, Jos 9:11, they mention no king, but simply state that they were sent by their elders and the inhabitants of their country; nor do we any where read of their king; and therefore we may naturally suppose that they had none.