Belah'dia (ベラフディア, Berafudia?) was a city-state in Thanalan in Final Fantasy XIV. It was the precursor to Ul'dah and Sil'dih, having split into the two city-states due to a succession crisis. Like its successor states, it was primarily ruled by Lalafell.
Belah'dia eventually faced a civil war between two princes - Sasawefu Ul Sisigan and Sasagan Ul Sisigan - who fought over the throne when their father grew ill. This civil war caused Belah'dia to split into the twin nations of Ul'dah and Sil'dih, each founded by one of the princes.
The most prominent site of ancient Belah'dia is the Sunken Temple of Qarn, an expansive temple complex that was devoted to worship of the sun goddess Azeyma. Many traps, including undead guardians, have been discovered in the ruins and continues to hinder research into the site. However, many scholars in Ul'dah speculate that Qarn was originally built by an even older civilization prior to being used by Belah'dia.