Thais is a direct descendant of Banor, the first human. Back in the day when the only settlement in Tibia was Tradespot, he was one of the courageous warriors defending this village against the vicious Orcs. His charisma enabled him to become the leader of a band of warriors and together they ensured Tradespot would not be overrun.
One day, however, the Orcs dealt him a deadly blow. Thais died in the arms of his son Tibianus, who would later be crowned the first king in Tibia and renamed Tradespot Thais, in honour of his father.
See also: A Visit to Thais