Joshua 11:1 (ESV)

1 When Jabin, king of Hazor, heard of this, he sent to Jobab king of Madon, and to the king of Shimron, and to the king of Achshaph,

The precise size and location of Madon is unknown, though the name could be a variant of Merom, which is mentioned in Joshua 11:5 and Joshua 11:7.1