Hello!

According to the examination rules, homophones of place names can be applied for trademarks. But only for the homophony of place names, if you just add a modifying word before the place name, it will not work, and it still cannot be registered. So "Old Yangzhou" as you call it cannot be registered. You can change "Yangzhou" to have the same pronunciation but different characters, such as: Yangzhou, Yangzhou, Yangzhou, Yangzhou, etc....