Bandalong was the chief city on Tleilax, the prime world of the Bene Tleilax. Entrance was forbidden to outsiders, the explanation given was that the majority of the city was considered holy and 'religious' by the Tleilaxu.
Thousands of years later, one sees that the city only came alive at the command of the Master of Masters Tylwyth Waff, who heralded the dawn with the cry of the Abdl, "The Sun is not God".
The Masters of the Bene Tleilax order convened on Bandalong in ghufran of kehl to further their plan for Bodal - the ultimate revenge - and a rise to power, after the decline of God-Emperor Leto Atreides II - whom they called God's Messenger - though this ascension never occurred. Bandalong, along with many Tleilaxu Masters within the city, was almost completely destroyed in an attack by the Honored Matres.